Ahh. You modified your projects after the event and before I replied. There was no mature content project on your account when I checked.
But you still did not answer who told you, that you were flagged nsfw. Where does this information come from? Did your settings display that message about adult content being uploaded? Did you get an email from support?
Or did you just notice that you were no longer indexed and assumed? You could have clicked the checkbox accidentally when uploading the 5th project and the delisting could have any unlrelated reason.
Because, well, there is no "store" page. You do not have a store on Itch. Itch is project based. You can have mixed projects on the same account. Even if your fifth project would have the meta info about mature content, the other four would have still been searchable from accounts that have adult content disabled.
Also this setting lock, afaik, is made precisly because publishers uploading make a fuss when not finding their projects, and forgot that they have it disabled in settings.
If you search for an account name, things are a bit different, but recent changes in the search results might have changed this. Previously the search results included account names. Now it is only projects. And please do not tell me, you assumed you were flagged, because you could not find your account name ;-)
Oh, and I do not believe there are any automated checks for nsfw content that is not labeled such. I have seen a fair share of games that should have been clearly labeled nsfw, but were not. And automated system would have caught those easily. But someone might have reported you for being miscategorized. But if that image is supposed to be the offending one, I have to laugh very loud. Look at the sfw browse page one, at all the horror games there.
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For anyone finding this, while you can mix projects on the same account, it is not a good idea to have 18+ and sfw content on the same account. You would not want the kids playing your teletubby simulator checking out your gore horror slash game, when visiting your profile.