(1) Use ublock origin to block reels, comment section and other features

(2) Wipe history and only watch productive topics on your account. Watch all other videos on incognito - I set up violentmonkey scripts to help. Here's a cool secret: your feed will ONLY be related to the videos in your history. My feed is now ONLY ML and music

(3) Delete the app on the phone. Only use youtube through firefox (if you have android) which allows the ublock extension

(4) Alternatives like newpipe helped before I stumbled onto this solution

You still need a little willpower. Find the strength to not use youtube for 3 weeks. Then it becomes much easier

Edit: clarity