Update.
the website was using cloudflare, and the client had the same domain in more than one of our services, so he wasn't even using the Enhance service for that specific domain.. so he didn't have to change the domain IP, and that's what caused the 404 error.
Every backup of that domain was almost empty, because that's exactly what he has on that plan, nothing, since wasn't being used. So every backup was correctly succeded.
The 4.7GB of data of backup is from it seems a subdomain he has there.
At the end, the move website between servers worked correctly, the backups were working correctly too on Enhance side.