diff --git a/changelog.d/reduce-flaky-tests.skip b/changelog.d/reduce-flaky-tests.skip
new file mode 100644
index 000000000..0375762c0
--- /dev/null
+++ b/changelog.d/reduce-flaky-tests.skip
@@ -0,0 +1 @@
+Reduce the number of flaky tests by making them sync if they affect the global state, and silence noisy test output.
diff --git a/config/test.exs b/config/test.exs
index 4da2b4f57..9652b7d4b 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -102,7 +102,6 @@ config :pleroma, :http, send_user_agent: false
 
 rum_enabled = System.get_env("RUM_ENABLED") == "true"
 config :pleroma, :database, rum_enabled: rum_enabled
-IO.puts("RUM enabled: #{rum_enabled}")
 
 config :joken, default_signer: "yU8uHKq+yyAkZ11Hx//jcdacWc8yQ1bxAAGrplzB0Zwwjkp35v0RK9SO8WTPr6QZ"
 
@@ -192,7 +191,7 @@ config :pleroma, Pleroma.Application,
   streamer_registry: false,
   test_http_pools: true
 
-config :pleroma, Pleroma.Web.Streaming, sync_streaming: true
+config :pleroma, Pleroma.Web.Streamer, sync_streaming: true
 
 config :pleroma, Pleroma.Uploaders.Uploader, timeout: 1_000
 
@@ -207,8 +206,9 @@ config :pleroma, Pleroma.User.Backup, tempdir: "test/tmp"
 
 if File.exists?("./config/test.secret.exs") do
   import_config "test.secret.exs"
-else
-  IO.puts(
-    "You may want to create test.secret.exs to declare custom database connection parameters."
-  )
 end
+
+# Avoid noisy shutdown logs from os_mon during tests.
+config :os_mon,
+  start_cpu_sup: false,
+  start_memsup: false
diff --git a/lib/mix/tasks/pleroma/config.ex b/lib/mix/tasks/pleroma/config.ex
index 8b3b2f18b..834b4fe14 100644
--- a/lib/mix/tasks/pleroma/config.ex
+++ b/lib/mix/tasks/pleroma/config.ex
@@ -330,7 +330,13 @@ defmodule Mix.Tasks.Pleroma.Config do
     |> Enum.each(&write_and_delete(&1, file, opts[:delete]))
 
     :ok = File.close(file)
-    System.cmd("mix", ["format", path])
+
+    # Ensure `mix format` runs in the same env as the current task and doesn't
+    # emit config-time stderr noise (e.g. dev secret warnings) into `mix test`.
+    System.cmd("mix", ["format", path],
+      env: [{"MIX_ENV", to_string(Mix.env())}],
+      stderr_to_stdout: true
+    )
   end
 
   defp config_header, do: "import Config\r\n\r\n"
diff --git a/lib/pleroma/upload/filter/exiftool/read_description.ex b/lib/pleroma/upload/filter/exiftool/read_description.ex
index 8c1ed82f8..8283b8643 100644
--- a/lib/pleroma/upload/filter/exiftool/read_description.ex
+++ b/lib/pleroma/upload/filter/exiftool/read_description.ex
@@ -29,22 +29,26 @@ defmodule Pleroma.Upload.Filter.Exiftool.ReadDescription do
     do: current_description
 
   defp read_when_empty(_, file, tag) do
-    try do
-      {tag_content, 0} =
-        System.cmd("exiftool", ["-b", "-s3", tag, file],
-          stderr_to_stdout: false,
-          parallelism: true
-        )
+    if File.exists?(file) do
+      try do
+        {tag_content, 0} =
+          System.cmd("exiftool", ["-m", "-b", "-s3", tag, file],
+            stderr_to_stdout: false,
+            parallelism: true
+          )
 
-      tag_content = String.trim(tag_content)
+        tag_content = String.trim(tag_content)
 
-      if tag_content != "" and
-           String.length(tag_content) <=
-             Pleroma.Config.get([:instance, :description_limit]),
-         do: tag_content,
-         else: nil
-    rescue
-      _ in ErlangError -> nil
+        if tag_content != "" and
+             String.length(tag_content) <=
+               Pleroma.Config.get([:instance, :description_limit]),
+           do: tag_content,
+           else: nil
+      rescue
+        _ in ErlangError -> nil
+      end
+    else
+      nil
     end
   end
 end
diff --git a/lib/pleroma/upload/filter/exiftool/strip_location.ex b/lib/pleroma/upload/filter/exiftool/strip_location.ex
index 1744a286d..23346d234 100644
--- a/lib/pleroma/upload/filter/exiftool/strip_location.ex
+++ b/lib/pleroma/upload/filter/exiftool/strip_location.ex
@@ -16,11 +16,12 @@ defmodule Pleroma.Upload.Filter.Exiftool.StripLocation do
 
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
     try do
-      case System.cmd("exiftool", ["-overwrite_original", "-gps:all=", "-png:all=", file],
+      case System.cmd("exiftool", ["-m", "-overwrite_original", "-gps:all=", "-png:all=", file],
+             stderr_to_stdout: true,
              parallelism: true
            ) do
         {_response, 0} -> {:ok, :filtered}
-        {error, 1} -> {:error, error}
+        {error, _} -> {:error, error}
       end
     rescue
       e in ErlangError ->
diff --git a/lib/pleroma/web/streamer.ex b/lib/pleroma/web/streamer.ex
index aba42ee78..120e94751 100644
--- a/lib/pleroma/web/streamer.ex
+++ b/lib/pleroma/web/streamer.ex
@@ -300,7 +300,7 @@ defmodule Pleroma.Web.Streamer do
     end)
   end
 
-  defp do_stream("user", item) do
+  defp do_stream("user", %Activity{} = item) do
     Logger.debug("Trying to push to users")
 
     recipient_topics =
diff --git a/mix.exs b/mix.exs
index 9e7ce7d4e..21ddcfd0c 100644
--- a/mix.exs
+++ b/mix.exs
@@ -230,7 +230,7 @@ defmodule Pleroma.Mixfile do
       "ecto.rollback": ["pleroma.ecto.rollback"],
       "ecto.setup": ["ecto.create", "ecto.migrate", "run priv/repo/seeds.exs"],
       "ecto.reset": ["ecto.drop", "ecto.setup"],
-      test: ["ecto.create --quiet", "ecto.migrate", "test --warnings-as-errors"],
+      test: ["ecto.create --quiet", "pleroma.ecto.migrate --quiet", "test --warnings-as-errors"],
       docs: ["pleroma.docs", "docs"],
       analyze: ["credo --strict --only=warnings,todo,fixme,consistency,readability"],
       copyright: &add_copyright/1,
diff --git a/test/mix/pleroma_test.exs b/test/mix/pleroma_test.exs
index e362223b2..e8f801913 100644
--- a/test/mix/pleroma_test.exs
+++ b/test/mix/pleroma_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Mix.PleromaTest do
-  use ExUnit.Case, async: true
+  use ExUnit.Case, async: false
   import Mix.Pleroma
 
   setup_all do
diff --git a/test/mix/tasks/pleroma/app_test.exs b/test/mix/tasks/pleroma/app_test.exs
index 65245eadd..6156214c1 100644
--- a/test/mix/tasks/pleroma/app_test.exs
+++ b/test/mix/tasks/pleroma/app_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Mix.Tasks.Pleroma.AppTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
 
   setup_all do
     Mix.shell(Mix.Shell.Process)
diff --git a/test/mix/tasks/pleroma/database_test.exs b/test/mix/tasks/pleroma/database_test.exs
index 38ed096ae..19df17b60 100644
--- a/test/mix/tasks/pleroma/database_test.exs
+++ b/test/mix/tasks/pleroma/database_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Mix.Tasks.Pleroma.DatabaseTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   use Oban.Testing, repo: Pleroma.Repo
 
   alias Pleroma.Activity
diff --git a/test/pleroma/http_test.exs b/test/pleroma/http_test.exs
index 7b6847cf9..e673e6591 100644
--- a/test/pleroma/http_test.exs
+++ b/test/pleroma/http_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.HTTPTest do
-  use ExUnit.Case, async: true
+  use ExUnit.Case, async: false
   use Pleroma.Tests.Helpers
 
   import Tesla.Mock
diff --git a/test/pleroma/repo/migrations/autolinker_to_linkify_test.exs b/test/pleroma/repo/migrations/autolinker_to_linkify_test.exs
index 99522994a..c15967eee 100644
--- a/test/pleroma/repo/migrations/autolinker_to_linkify_test.exs
+++ b/test/pleroma/repo/migrations/autolinker_to_linkify_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Repo.Migrations.AutolinkerToLinkifyTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   import Pleroma.Factory
   import Pleroma.Tests.Helpers
   alias Pleroma.ConfigDB
diff --git a/test/pleroma/upload/filter/exiftool/strip_location_test.exs b/test/pleroma/upload/filter/exiftool/strip_location_test.exs
index 4dcd4dce3..485060215 100644
--- a/test/pleroma/upload/filter/exiftool/strip_location_test.exs
+++ b/test/pleroma/upload/filter/exiftool/strip_location_test.exs
@@ -25,8 +25,8 @@ defmodule Pleroma.Upload.Filter.Exiftool.StripLocationTest do
 
       assert Filter.Exiftool.StripLocation.filter(upload) == {:ok, :filtered}
 
-      {exif_original, 0} = System.cmd("exiftool", ["test/fixtures/DSCN0010.#{type}"])
-      {exif_filtered, 0} = System.cmd("exiftool", ["test/fixtures/DSCN0010_tmp.#{type}"])
+      {exif_original, 0} = System.cmd("exiftool", ["-m", "test/fixtures/DSCN0010.#{type}"])
+      {exif_filtered, 0} = System.cmd("exiftool", ["-m", "test/fixtures/DSCN0010_tmp.#{type}"])
 
       assert String.match?(exif_original, ~r/GPS/)
       refute String.match?(exif_filtered, ~r/GPS/)
diff --git a/test/pleroma/web/activity_pub/mrf/remote_report_policy_test.exs b/test/pleroma/web/activity_pub/mrf/remote_report_policy_test.exs
index 8d2a6b4fa..270c650e0 100644
--- a/test/pleroma/web/activity_pub/mrf/remote_report_policy_test.exs
+++ b/test/pleroma/web/activity_pub/mrf/remote_report_policy_test.exs
@@ -1,5 +1,5 @@
 defmodule Pleroma.Web.ActivityPub.MRF.RemoteReportPolicyTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
 
   alias Pleroma.Web.ActivityPub.MRF.RemoteReportPolicy
 
diff --git a/test/pleroma/web/activity_pub/utils_test.exs b/test/pleroma/web/activity_pub/utils_test.exs
index a48639c38..f162f3684 100644
--- a/test/pleroma/web/activity_pub/utils_test.exs
+++ b/test/pleroma/web/activity_pub/utils_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.UtilsTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   alias Pleroma.Activity
   alias Pleroma.Object
   alias Pleroma.Repo
diff --git a/test/pleroma/web/activity_pub/views/user_view_test.exs b/test/pleroma/web/activity_pub/views/user_view_test.exs
index 7ac5f7c0f..a3f807ca9 100644
--- a/test/pleroma/web/activity_pub/views/user_view_test.exs
+++ b/test/pleroma/web/activity_pub/views/user_view_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.UserViewTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   import Pleroma.Factory
 
   alias Pleroma.User
diff --git a/test/pleroma/web/pleroma_api/views/chat_message_reference_view_test.exs b/test/pleroma/web/pleroma_api/views/chat_message_reference_view_test.exs
index c78c03aba..8c3682798 100644
--- a/test/pleroma/web/pleroma_api/views/chat_message_reference_view_test.exs
+++ b/test/pleroma/web/pleroma_api/views/chat_message_reference_view_test.exs
@@ -4,7 +4,7 @@
 
 defmodule Pleroma.Web.PleromaAPI.ChatMessageReferenceViewTest do
   alias Pleroma.NullCache
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
 
   alias Pleroma.Chat
   alias Pleroma.Chat.MessageReference
@@ -18,6 +18,11 @@ defmodule Pleroma.Web.PleromaAPI.ChatMessageReferenceViewTest do
   import Mox
   import Pleroma.Factory
 
+  setup do
+    Mox.stub_with(Pleroma.CachexMock, Pleroma.NullCache)
+    :ok
+  end
+
   setup do: clear_config([:rich_media, :enabled], true)
 
   test "it displays a chat message" do
diff --git a/test/pleroma/web/rich_media/card_test.exs b/test/pleroma/web/rich_media/card_test.exs
index c69f85323..723446c86 100644
--- a/test/pleroma/web/rich_media/card_test.exs
+++ b/test/pleroma/web/rich_media/card_test.exs
@@ -4,7 +4,7 @@
 
 defmodule Pleroma.Web.RichMedia.CardTest do
   use Oban.Testing, repo: Pleroma.Repo
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
 
   alias Pleroma.Tests.ObanHelpers
   alias Pleroma.UnstubbedConfigMock, as: ConfigMock
@@ -19,6 +19,8 @@ defmodule Pleroma.Web.RichMedia.CardTest do
   setup do
     mock_global(fn env -> apply(HttpRequestMock, :request, [env]) end)
 
+    Mox.stub_with(Pleroma.CachexMock, Pleroma.NullCache)
+
     ConfigMock
     |> stub_with(Pleroma.Test.StaticConfig)
 
diff --git a/test/pleroma/web/streamer_test.exs b/test/pleroma/web/streamer_test.exs
index 096ca2d2a..f5008f6b9 100644
--- a/test/pleroma/web/streamer_test.exs
+++ b/test/pleroma/web/streamer_test.exs
@@ -19,7 +19,12 @@ defmodule Pleroma.Web.StreamerTest do
 
   @moduletag needs_streamer: true, capture_log: true
 
-  setup do: clear_config([:instance, :skip_thread_containment])
+  setup do
+    clear_config([:instance, :skip_thread_containment])
+    Mox.stub_with(Pleroma.CachexMock, Pleroma.NullCache)
+
+    :ok
+  end
 
   describe "get_topic/_ (unauthenticated)" do
     test "allows no stream" do
diff --git a/test/pleroma/web/web_finger_test.exs b/test/pleroma/web/web_finger_test.exs
index eb03c736e..da10abdd2 100644
--- a/test/pleroma/web/web_finger_test.exs
+++ b/test/pleroma/web/web_finger_test.exs
@@ -3,12 +3,13 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.WebFingerTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   alias Pleroma.Web.WebFinger
   import Pleroma.Factory
   import Tesla.Mock
 
   setup do
+    Mox.stub_with(Pleroma.CachexMock, Pleroma.NullCache)
     mock(fn env -> apply(HttpRequestMock, :request, [env]) end)
     :ok
   end
diff --git a/test/pleroma/workers/publisher_worker_test.exs b/test/pleroma/workers/publisher_worker_test.exs
index ca432d9bf..4519864a5 100644
--- a/test/pleroma/workers/publisher_worker_test.exs
+++ b/test/pleroma/workers/publisher_worker_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Workers.PublisherWorkerTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   use Oban.Testing, repo: Pleroma.Repo
 
   import Pleroma.Factory
diff --git a/test/pleroma/workers/reachability_worker_test.exs b/test/pleroma/workers/reachability_worker_test.exs
index 4854aff77..c641ccf65 100644
--- a/test/pleroma/workers/reachability_worker_test.exs
+++ b/test/pleroma/workers/reachability_worker_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Workers.ReachabilityWorkerTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   use Oban.Testing, repo: Pleroma.Repo
 
   import Mock
diff --git a/test/pleroma/workers/receiver_worker_test.exs b/test/pleroma/workers/receiver_worker_test.exs
index 7f4789f91..12abc1a27 100644
--- a/test/pleroma/workers/receiver_worker_test.exs
+++ b/test/pleroma/workers/receiver_worker_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Workers.ReceiverWorkerTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   use Oban.Testing, repo: Pleroma.Repo
 
   import Mock
diff --git a/test/pleroma/workers/remote_fetcher_worker_test.exs b/test/pleroma/workers/remote_fetcher_worker_test.exs
index 6eb6932cb..a3b900a9b 100644
--- a/test/pleroma/workers/remote_fetcher_worker_test.exs
+++ b/test/pleroma/workers/remote_fetcher_worker_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Workers.RemoteFetcherWorkerTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   use Oban.Testing, repo: Pleroma.Repo
 
   alias Pleroma.Workers.RemoteFetcherWorker