You've gotten lots of good advice for long-term improvement, and for the nuclear option; here are some short-term smaller fixes which are (much) better than nothing. The idea with these is to put up a little speedbump in the way of mindless consumption, but not so much of a barrier that you'll be tempted to remove it yourself.

- For Youtube, delete and disable watch history. This will make the "home" and "shorts" tabs blank, and make the below-video recommendations less effective. Your subscriptions and everything else will still work normally. Also uninstall the app from your phone, so you have to access it in a browser (even on Android you can "disable" it).

- For Reddit, block r/all (and maybe / (home)) in your adblocker on all your devices. (For ublock origin the rule is ||reddit.com/r/all^$document ) The block can easily be clicked through, but that means you'll leave it in place for next time. Non-r/all pages will still work. Again, uninstall any apps.

I don't have similar advice for Facebook and Twitch; maybe unfollow everyone on Twitch so you have to look up channels intentionally?