I’ve been using ungoogled-chromium for a few weeks when using youtube.
Tonight I tried logging in using Firefox and Brave and they are demanding my phone number else they can’t be sure it is me logging in.
This really is a new era in internet for me tonight. No f-ing way. Gonna start using the weights every night instead of rotting my brain.
Just don’t login and use a 3rd party tool to manage your subscriptions.
I’ve done everything from Freetube to yt-dlp. There’s always that one night when Goggle are ahead and you have to find something else to do. Might as well just do that everynight from now on.
Edit: Also what about age verification. I do like my police bodycam videos I have to admit. There’s too many videos where you have to login.
I’ve been using ungoogled for years. that is strange. I don’t have a youtube account though. I reckon they will play with for anybody for any reason at any time.
If we are all confess-y and everything I like the Ring package thief Fail vids myself….on freetube 
edit/word change
This morning it will allow me to login in again but I definitely need to stop assuming I will be able to watch youtube when I get home from work.