UPDATE 2
It seems that starting today, uBlock Origin is working to combat this Youtube Block. Mine started working again! Lets all thank the devs of UBO for fighting this fight!
UPDATE
So as new info comes out, I'll be posting it here. It seems as if this Rollout Has Several Parts.
Part 1
You get a popup message over top of your video, blocking the screen:
This is the first sign. If you see this popup AND are logged into a YouTube account, your account has been selected.
At this stage you can likely close or block these messages with an adblocker.
Part 2
This message will change, indicating that you have 3 remaining videos to watch without ads.
Will insert photo once one has been found
At this stage your adblocker will imminently stop working in 3 videos time.
Personally using Firefox + uBlock Origin and tweaking filters and updates does not even fix it.
Part 3
None of the video loads now, everything looks blank.
At this stage you must tred new ground to avoid ads. I have posted methods in the comments. If you want to bypass this end page, read down there.
End of Update
YouTube has started rolling out anti-adblock to users inside the United States, which means that they are preparing to roll this out to the entire country. Personally, I have been blocked already. I want to gauge how common this occurrence is.
I have a script I used to auto download new stuff from my subscriptions using yt-dlp. I never watch videos on youtube anymore because it's just garbage, buffering all the time or just straight up not playing content. The only thing I miss is sponsor block but I don't care that much
here's instructions on setting the script up if you're interested
I'll make an updated lemmy post as well but for now it's an old reddit post of mine. There's also some great alternatives that I think are easier to set up if you don't mind managing a separate subscriptions list - I made this script specifically because none of the options I'd seen were able to take your subscriptions from youtube and check them.
May be worth trying to set up with one of the alternative youtube frontends that have been popping up so you can use those accounts. I think it depends on if yt-dlp allows it as that's what's doing all the work here.