At xbox there's immoment the 3 month gamepass offer for 1 euro and I bought xbox live gold for one year this subscription expires on 04/27/2021 my gold subscription expires after the 3 month gamepass expires, so it's gone or is it still there until the actual process?
Your gold subscription will of course be retained because it has already been paid for.
If you subscribe to the Gamepass, your gold will become the Gamepass Ultimate for the period.