Hi @giacomo_bucket - I have experienced this before, actually - when I was deploying some starter repos for example to play around with some static site generators. The sites were live, but when I logged into Netlify.com I couldn’t see them. It was very odd.
Then I realized that due to being logged in via SSO/github, the new sites were actually being created under a different email with Netlify than I had originally set up manually. (To be really clear - I actually had two netlify accounts as my github email is a different one than my manually created Netlify account).
Can you confirm that you’re not experiencing the same situation I am describing above? This would definitely explain why you have “ghost” sites.