Maybe he could try to post another comment instead of the same one to pinpoint what's triggering this. There is a separate % sign, maybe a few words together causing filters to act.
His method is not proving anything because he keeps trying the same thing.
In the comments he describes the issue in more detail. In this case the word "poof" is being flagged for comment deletion and other people were encouraged to try posting it and their comments were also deleted.
I wanted to copy-paste the comment here but for some reason YouTube makes that difficult on my phone.
oh... that started much longer ago. Back in the earlier GUI days you could rely on copy/paste to work, now that everything is a web app, it's total pot luck if you can even copy/paste inside the same app, let alone across different apps.
His method is not proving anything because he keeps trying the same thing.