Filter the parsed OpenGraph/Twittercard tags and only retain the ones we intend to use.

lib/pleroma/web/rich_media/parsers/twitter_card.ex

@@ -11,5 +11,16 @@ defmodule Pleroma.Web.RichMedia.Parsers.TwitterCard do
     |> MetaTagsParser.parse(html, "og", "property")
     |> MetaTagsParser.parse(html, "twitter", "name")
     |> MetaTagsParser.parse(html, "twitter", "property")
+    |> filter_tags()
+  end
+
+  defp filter_tags(tags) do
+    Map.filter(tags, fn {k, _v} ->
+      cond do
+        k in ["card", "description", "image", "title", "ttl", "type", "url"] -> true
+        String.starts_with?(k, "image:") -> true
+        true -> false
+      end
+    end)
   end
 end