Depending on which youtube player alternative you choose, be prepared for “downtime” when YouTube decides to change things on their part which breaks, at least temporarily these apps (but who knows for how long and what the future holds) .
I cannot talk to GrayJay as I don’t use it. I have tried it a short while but it doesn’t match my use case of only watching YouTube videos. I tried it both on Linux and Android. The android app was among the “most feature rich” for not saying “bloated” I have had on my phone with an enormous size. The Linux one as well, to my test. I like normally apps with minimal but not simplistic UI which does one (or just a few things) and do it (them) well.
At any case, whatever you will choose which matches your use case, equip yourself with some patience and frustration management. Because YouTube.
Search for FreeTube on the forum and you will get an idea. Here is one recent:
Just my two Yuans.