It may have been the channel owner, or more likely it may have been YouTube itself.

There have been a few discussions over at level1techs where people thought they thought the channel was moderating them for some strange reason, only to turn out it’s YouTube: https://forum.level1techs.com/t/l1t-youtube-shadowban-shadow...

More than once I’ve made a comment, went to edit a spelling mistake, and got an error on save because my completely unobjectionable comment was removed 10 seconds after posting.

YouTube has a horrible comment automation wordfilter/AI that will silently steamroll comments in a way that makes Reddit and 4chan mods seem rational. The channel owners don’t even see the comments (and last I checked, they don’t show up in your comment history either)

YouTube comments are vapid, in part because anything high effort/quality is likely to get deleted.

Yes, you can confirm if this is the case by going to "Your data in Youtube" and seeing if your comment still shows up there. If you click the direct link there it'll even take you to the video and highlight your comment. But if you reload the video without the querystring part that identifies your comment, you won't see it. It's happened to a bunch of mine too on and off over the years, and it's not because of negativity or anything.

You can even see it happening to other people - if you see a comment tree that says it has N replies, but then you expand it and it shows less than N replies, the same thing happened to the people who posted those missing replies too.

The same thing happens with my Google Maps reviews too. Google is too lazy and high on their farts about letting automation do their moderation to care.