I use MullvadVPN and i have never encountered this issue before. Hopefully won't need to either.
I'll tell you another weird detail I found out today..
A lot if my coworkers had their uBlock terminated by the chrome browser. I use Ubuntu with chromium because reasons and somehow, my uBlock is still active and working o.o it has not been terminated and I still get rid of those nasty YouTube ads.
I use Mullvad but get a "confirm you're not a bot by signing in" message occasionally. All I do is switch servers and clear all history/cookies/etc. It works 95% of the time.
It does, I've found Albania, Estonia and Nigeria skip the issue at least. If anyone else got server recommendations that work feel free to drop! I should probably clarify that my Mullvad connection is a barebones Wireguard one running on top of Tailscale
Sometimes the more commonly used servers like UK start working for a few hours/days but that never lasts. The 3 listed are basically bulletproof in my experience though
And yea, using a frontend will not bypass this. Unless that frontend is an online downloader like Cobalt.tools or amp4.cc. Or Invidious I guess but that... Has its own issues
This maybe affects Mullvad so strongly cause they never bother hididng/swapping their server IPs and don't have a particularly large plethora of them unlike competitors?