I have the feeling YouTube removes my comments if I edit them shortly after creating them.
Also, it feels like they remove comments quickly if they are reported often. At least I have the feeling that if I post factual but unpopular comments, they are more likely to get removed after a short while.
Anyway, it makes sense they remove more than they used to as they had a big spam problem. Now it's better but them removing valid comments too quickly as collateral makes sense to me.