Add fallback for people that used reddit in the comments API and their preferences

src/invidious/exceptions.cr

@@ -50,3 +50,9 @@ class InvalidVideoID < InfoException
     return "Invalid video ID '#{id}'"
   end
 end
+
+class RedditIsDeprecated < InfoException
+  def message
+    return "Reddit comments have been removed from Invidious."
+  end
+end

src/invidious/routes/api/v1/videos.cr

@@ -346,6 +346,18 @@ module Invidious::Routes::API::V1::Videos
     continuation = env.params.query["continuation"]?
     sort_by = env.params.query["sort_by"]?.try &.downcase
 
+
+    # 2026-10-18: Make a mechanism to remove unused
+    # preferences from PREFS cookie of the clients
+    # when some preferences are changed, like this one
+    # which is a Reedit comments deprecation that appears
+    # on preferences.
+    #
+    # Fallback for API users that still use Reddit as a source
+    if source == "reddit"
+      return error_json(410, RedditIsDeprecated.new)
+    end
+
     if source == "youtube"
       sort_by ||= "top"
 

src/invidious/routes/watch.cr

@@ -74,11 +74,24 @@ module Invidious::Routes::Watch
     if nojs
       if preferences
         source = preferences.comments[0]
+        # 2026-10-18: Make a mechanism to remove unused
+        # preferences from PREFS cookie of the clients
+        # when some preferences are changed, like this one
+        # which is a Reedit comments deprecation that appears
+        # on preferences.
+        #
+        # Fallback for people that have reddit in their prefs
+        source = preferences.comments[1] if source == "reddit"
 
         if source.empty?
           source = preferences.comments[1]
+        end
+
+        if source == "youtube"
           comment_html = JSON.parse(Comments.fetch_youtube(id, nil, "html", locale, preferences.thin_mode, region))["contentHtml"]
         end
+      else
+        comment_html = JSON.parse(Comments.fetch_youtube(id, nil, "html", locale, preferences.thin_mode, region))["contentHtml"]
       end
 
       comment_html ||= ""