Introducing friction to reduce addiction
I'm far from the first person to observe that major component of internet addiction is "reduced friction." So much of the modern internet is built to immediately satisfy your impulses. I've discussed this topic a bit before, but my general thesis is that people confuse convenience with something removes the need to practice impulse control.
In any case, I've been using Librewolf instead of Firefox, as Mozilla is slowly driving Firefox into the ground. Out of the box, Librewolf does not save your history / cookies / etc. This is done as a privacy measure, but it has an accidental side effect: when you go to visit a website and start typing it into the address bar, there's nothing to autocomplete. You cannot type "ol" and have the browser dump all of "old.reddit.com" in immediately. This had almost become a nervous tic: ctrl + tab + "ol" (or "ne" for news.ycombinator.com) -- any time I got bored. Same with youtube, or anything else. I didn't plan for it, but once my URLs were not autocompleting, I found the old tic was fairly well neutered. I can still go visit youtube or whatever time-waster, obviously, but I have to actually mean it. I need to type the whole address and hit enter. So really, I'm recommending:
Clear history between browsing sessions to remove the auto-completion of previously visited URLs.
That may seem small, or may even seem crazy, but it makes a much bigger difference than you'd think. Try it out sometime! You can erase your browser history between sessions without dumping your site cookies or anything, so it's not as if you'll lose logins. I would honestly bet that for most of you, you waste less time online.