It might just be a coincidence but I've had a lot of trouble using Invidious or Piped lately too. Videos load and titles load, but video thumbnails don't load for me.
Google is blocking popular instances these days, so yeah, you basically need to find an unpopular instance, which usually means it's new and may not live for long, or it will quickly become popular, because it works, which will cause Google to block it.
I tried it and my main complaint was it was like 720p, so lower quality (noticeable to me just looking at it). But it "just worked" for me. But I'm also not interested in YouTube enough to play this game - if they block me, I stop going there. It seems like they give up blocking me every so often (or something updates IDK).
Yeah I might try the others a couple more times before giving up but it's not gone well for me thusfar. Libreddit and invidious worked for me for like 4 days last time, both crapped out about the same time. It's annoying to have to repeatedly troubleshoot what used to be something you could basically count on working