I think this happens all the time.

I very rarely post comments on youtube, but when I do, I often want to go back to see if I've gotten any replies. Anyone else who's tried doing this has figured out that youtube makes it incredibly difficult for you to find your comment history. It's clearly not something they intend for you to actually use. They don't give you notifications about replies, or even the option to be notified.

Anyway, I think a lot of my comments have either been silently deleted or that maybe they work as if I'm shadowbanned. I've seen this in action trying to post comments on a news video.