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?