I have been using the Youtube app to watch on my Roku tvs for several years. Recently all my Youtube accounts disappeared from one tv. I'm now using my Roku tv as a monitor (just for youtube), with a Geekom Mini Pc (Windows 11) as a source. It's also nice to be able to see comments about the videos, and much easier to do searches.
You can can these mini pcs (with dual 4k HDMI ports) for as low as $200 at Amazon.
We'll see how long it lasts (works).