Testing it out and it defaults to 720p30 (30fps I assume). When I switch it to 1080p60, video playback begins to freeze/lag. So, sticking with revamced for now.
This seems to be a problem with every third-party YouTube client. NewPipe, LibreTube, and Piped all have the same issue for me. They desperately need better buffering logic. I suspect Google is doing something on their end to make this harder than it needs to be.
As far as I remember, if the client does not say "hello" in a proper way, YT will limit the bandwidth to the point it's unwatchable. It sometimes affect NewPipe and Kodi.