Using Classic Outlook on Windows for personal email, calendar, and contact management
I really want to tell you some good news. However, according to Microsoft policy, once you delete an alias ending in @hotmail and replace it with your Gmail account, the change is permanent and the Hotmail address cannot be restored or reused. Your Gmail account is now your new login email and can be used to send or receive emails.
Microsoft mentioned this policy here: https://support.microsoft.com/office/add-or-remove-an-email-alias-in-outlook-com-459b1989-356d-40fa-a689-8f285b13f1f2