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As user viewer (not channel owner) I have setup YouTube history to be only for max 3 months. Then auto-delete. Today I checked that this setting applies only to users' Video Watch History.

One has to manually go https://myactivity.google.com/page?page=youtube_comment_likes to delete Your Likes and Dislikes on YouTube and

delete comments at https://myactivity.google.com/page?hl=en&utm_medium=web&utm_source=youtube&page=youtube_comments for deleting Youtube Comments.