I didn't know jewtube had 4K videos. There is that 1080 enhanced, whatever that is, but jewtube for me is just background noise. Never cared about video quality.
Well it's 2160 or something like that; I'm partially blind so the higher resolution the better for me. I'll watch the Outdoor Boys, Baumgarter restorations and Wriswatch revival vids on the jewtubes.
Are you using a PC or the TV app/streaming to a TV?
I don't have any problems with 2160 videos on a PC using Brave browser and Unlock.
Anything involving a TV and YT aside from using it as a PC display is turbo fucked. They put extra ads in if you're watching it via a smart TV.