Youtube stopped working out of nowhere for me. In one day, when it previously worked fine, all of a sudden it would never get past the initial load screen (just YouTube logo) and then it would timeout and me it couldn't connect. It was still working on our other TV. So I uninstalled and reinstalled it multiple times. I even did an entire factory reset. Nothing!
Finally, I tried switching from a wired connection to wireless and then YouTube finally worked. Note: Several other channels were working fine while connected via wired connection: Netflix, Disney +, PlutoTV, etc. It seemed to be only YouTube.
So I can currently watch YouTube videos, but it seems it only works with a wireless connection.
My Roku:
Hisense 50R7+, 7218X, v. 12.5.5. Build 4173-39
Youtube: v 2.20 build 110005159