Right, this is why I’m always very skeptical about these claims, because I’ve seen people making claims, that are not general, and certainly not applied to everyone. I myself, have seen that happen. My top 3 hypothesis are:

• There is an AI moderation happening, that most likely is targeting, not specific words, but rather specific manners of writing. I believe this is to prevent the huge amounts of bots that are constantly targeting the comment section, sometimes with scams, and have on several occasions become a very problematic issue. They still are, but it seems they come in waves… Like, imagine a new bot comes along, writes sentences on a specific pattern, and until that pattern is added to the AI moderation thing, they persist. Once they train the AI to pick up those new bots patterns of writing, the bots then poof, and in the process, may also target non-bots. For example, lately, one of the patterns of the new wave of bots is that they always end the post with 2 emojis. So it is feasible that the AI tool has learned that whoever uses 2 consecutive emojis, is a bot.
• The YouTube comment section (and even YouTube as a whole), has been plagued with bugs, and it is a very old site, which is inheriting old code, and the web has dramatically changed in the last decade or so. So they are only doing patches over the code, and that is not always the best. There comes a point where it’s better if you just ditch the old code, and start something “newer”
• YouTube relies on cloud services, all around the world, so there is a chance that the platform prioritizes syncing more important data, such has views, likes, and things that more directly apply to the monetization of the channel, which is a very tiny amount of data, when compared with all the comments. So it is plausible, that some comments are either being dropped to “save” bandwidth and data transfer, or synced at a later time, because they aren’t relevant for YouTube’s business model, which is, sell advertisement.

I’m always skeptical about these “YouTube is censoring X word in comments”. Can you please post the link to the video? And have you also tried to change the SORT_BY from TOP COMMENTS to NEWEST FIRST? YouTube will in a somewhat random manner, just “hide” some comments, for whatever dumb reason, from the TOP COMMENTS, but show all if you pick NEWEST FIRST.