This message doesn’t sound logical - in my opinion if your app wasn’t published on a web domain, it wouldn’t be accessible. In my understanding such error may appear after new pricing plans were introduced.
Based on a quick search on the forum, this problem might happen with some accounts on free tier and could be resolved by Adalo Support. I’d suggest submitting a support ticket here: Submit a Support Ticket
Just in case, here are the posts I’m referring to:
