As a workaround, you can add puglia.it to your account and then delete the hosting for it. It won’t really harm anything for the moment.
You could also just submit a ticket to support about this. I don’t think they’re totally aware of all the subdomains that allow/require independent hosting - like co.uk, etc.
Do let us know what support says about this, as it will be very helpful to others who want to host similar domains.
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