I use youtube across different devices with the same account. sometimes, i even use it in multiple browser profiles or apps on the same device (with the account logged in).
the ad reminder got me. it actually stopped serving any youtube video on my laptop. so i made a new profile in firefox, logged in, and it was fine. for a couple days.
so i made a new profile, logged in, and... was foiled. but not to be deterred, i did what any reasonable person would do: i sought out one of the DOZENS of alternative frontends and used youtube's recommendation algorithm on the main site to pull videos from the alternative frontend.
for one day.
today, on my laptop, with my old profile, never changing logins or browser settings, youtube started working again.
did we win?
These apps work like a dream for me on every ios device:
https://apps.apple.com/us/app-bundle/fizzy-water-bundle/id1601247237
No ads, no pop-ups, native iOS video player (including airplay, PiP, Now Playing integration and audio controls with the screen locked).
Vinegar - Youtube
Baking Soda - Most other videos on the internet