I managed to login and leave a comment, maybe logout and re-login. Then leave a comment on a different video (I just commented on a random Mr Beast Video)
Does it work if you turn off Shields? I’m wondering if it might be something in your fingerprint settings, a chat filter, or whatever.
I’d try to toy with things myself but no longer keep any newer Android devices to test with. If not Shields, the next thing I’d ask you about is if it might work in Private window? I’m wondering if could be a bad cookie or something.