diff --git a/src/components/conversation/conversation.js b/src/components/conversation/conversation.js
index 73aaa2358..f05af6f36 100644
--- a/src/components/conversation/conversation.js
+++ b/src/components/conversation/conversation.js
@@ -239,9 +239,9 @@ const conversation = {
                 depth,
               },
               walk(forest, forest[id], depth + 1, processed),
-            ].reduce((a, b) => a.concat(b), [])
+            ].flat()
           })
-          .reduce((a, b) => a.concat(b), [])
+          .flat()
 
       const linearized = walk(
         threads.forest,
diff --git a/src/components/emoji_picker/emoji_picker.js b/src/components/emoji_picker/emoji_picker.js
index ac9952b9b..a0e30bf6d 100644
--- a/src/components/emoji_picker/emoji_picker.js
+++ b/src/components/emoji_picker/emoji_picker.js
@@ -408,7 +408,7 @@ const EmojiPicker = {
             isFirstRow: index === 0,
           })),
         )
-        .reduce((a, c) => a.concat(c), [])
+        .flat()
     },
     languages() {
       return ensureFinalFallback(
diff --git a/src/services/theme_data/iss_utils.js b/src/services/theme_data/iss_utils.js
index 67579a118..d42da3780 100644
--- a/src/services/theme_data/iss_utils.js
+++ b/src/services/theme_data/iss_utils.js
@@ -24,7 +24,7 @@ export const getAllPossibleCombinations = (array) => {
       const nonSelf = array.filter((x) => !selfSet.has(x))
       return nonSelf.map((x) => [...self, x])
     })
-    const flatCombos = newCombos.reduce((acc, x) => [...acc, ...x], [])
+    const flatCombos = newCombos.flat()
     const uniqueComboStrings = new Set()
     const uniqueCombos = flatCombos.map(sortBy).filter((x) => {
       if (uniqueComboStrings.has(x.join())) {
@@ -36,7 +36,7 @@ export const getAllPossibleCombinations = (array) => {
     })
     combos.push(uniqueCombos)
   }
-  return combos.reduce((acc, x) => [...acc, ...x], [])
+  return combos.flat()
 }
 
 /**
diff --git a/src/services/theme_data/theme2_to_theme3.js b/src/services/theme_data/theme2_to_theme3.js
index 9ea319175..96955edfd 100644
--- a/src/services/theme_data/theme2_to_theme3.js
+++ b/src/services/theme_data/theme2_to_theme3.js
@@ -559,9 +559,9 @@ export const convertTheme2To3 = (data) => {
 
   const flatExtRules = extendedRules
     .filter(Boolean)
-    .reduce((acc, x) => [...acc, ...x], [])
+    .flat()
     .filter(Boolean)
-    .reduce((acc, x) => [...acc, ...x], [])
+    .flat()
 
   return [
     generateRoot(),
diff --git a/src/services/theme_data/theme_data_3.service.js b/src/services/theme_data/theme_data_3.service.js
index 507b384db..465062225 100644
--- a/src/services/theme_data/theme_data_3.service.js
+++ b/src/services/theme_data/theme_data_3.service.js
@@ -262,7 +262,7 @@ export const init = ({
           ...r,
         })),
       )
-      .reduce((acc, arr) => [...acc, ...arr], []),
+      .flat()
     ...inputRuleset,
   ].map((rule) => {
     normalizeCombination(rule)
@@ -705,7 +705,7 @@ export const init = ({
       .map((variant) => {
         return stateCombinations.map((state) => ({ variant, state }))
       })
-      .reduce((acc, x) => [...acc, ...x], [])
+      .flat()
 
     stateVariantCombination.forEach((combination) => {
       combination.component = component.name
diff --git a/src/stores/emoji.js b/src/stores/emoji.js
index 2d77954f1..8135a483e 100644
--- a/src/stores/emoji.js
+++ b/src/stores/emoji.js
@@ -120,23 +120,19 @@ export const useEmojiStore = defineStore('emoji', {
       }, {})
     },
     standardEmojiList(state) {
-      return (
-        SORTED_EMOJI_GROUP_IDS.map((groupId) =>
-          (this.emoji[groupId] || []).map((k) =>
-            injectAnnotations(k, this.unicodeEmojiAnnotations),
-          ),
-        ).reduce((a, b) => a.concat(b), []) ?? []
-      )
+      return SORTED_EMOJI_GROUP_IDS.map((groupId) =>
+        (this.emoji[groupId] || []).map((k) =>
+          injectAnnotations(k, this.unicodeEmojiAnnotations),
+        ),
+      ).flat()
     },
     standardEmojiGroupList(state) {
-      return (
-        SORTED_EMOJI_GROUP_IDS.map((groupId) => ({
-          id: groupId,
-          emojis: (this.emoji[groupId] || []).map((k) =>
-            injectAnnotations(k, this.unicodeEmojiAnnotations),
-          ),
-        })) ?? []
-      )
+      return SORTED_EMOJI_GROUP_IDS.map((groupId) => ({
+        id: groupId,
+        emojis: (this.emoji[groupId] || []).map((k) =>
+          injectAnnotations(k, this.unicodeEmojiAnnotations),
+        ),
+      }))
     },
   },
   actions: {