That's a lie. Itch.io for sure have a shadowban - because my games isn't even seen by other people, even published. Today I published my game - it was on the "New games" in a tags for about 10 mins and then I realoaded a page - poof! - disappeared. I tried to sontact support about it by email, but support ignoring this issue (it's about barelyy ALL my games) - the oldest email they ignoring was sent 1st of SEPTEMBER! More than 2 months ago.
So yes, there is shadowban in itch.io system.
Itch sometimes delists projects, even developers. For example if they violate quality guidelines. If you call this a shadowban, yes, there are shadowbans. But in context I heard it, it was about things like ignoring devlogs or like arbitrary lowering ranking in popular sort.
But if your account were delisted, you could not have published your game at all on the index.
If it were visible a short amount of time, this would fit with people reporting your game. Or a coincidence in timing with other reports or automatic triggers putting your things in quarantine. Btw, you did notice that your patreon is unreachable?
There are a ton of patreons with nsfw content. But if this has been so for several months, than maybe some people seeing your games reported you for being an impostor, because they could not verify the patreon you link to from your profile.
Communication with devs could be better, but I also kinda understand why they tend not to tell people what is going on. Worst case they make it even more easy for scammers to upload their things. And best case, the dev does not even know about any investigation. And here it does not matter why there is any manual review. Be it to check eglibility for indexing or quarantine or whatever.
Two months is long but not unheard of and you also uploaded more games in that time, so maybe that put you at the back of the queue.
For quarantines, maybe. But it would rather put your releases and updates on the list to begin with.
There are two separate issues, but one looks similar to other if you do not know what it was. Quarantine and not being indexed. While on quarantine, a game is also not indexed.
For regular indexing problems, it has been observed that an update can put you on the manual review list. It stands to reason that it could also put you at the back of the list if you already were on the list. It has also been observed or even stated, that the waiting queue is not quite fifo. And the list of what triggers what, is secret after all. (And if I were to implement such a thing, I would even include random factors, to keep people guessing ;-)