The Apple ID created with gmail account say example1@gmail.com was permanently deleted from the gmail server , and if the account was set up with secondary authentication ( in which three answers for respective questions , date of birth , rescue mail address are added ) , the administrator can’t sign with iCloud account.
Sign in with rescue mail address in gmail account ( enter the password ) , click on personal info .
Click on edit , and try to add a new trusted number .
And can't further move , the bell icon shakes and stop if you click on send the code will go to the old trusted number that is inactive .
Click on more ways to verify , it again prompted to enter rescue mail address and password , Scroll down and click on account recovery icon , then add a new trusted number and click on next , the trusted number will add , the trick was using the rescue mail address that was attached to the primary mail address .
See this article also https://support.google.com/accounts/answer/6294825?hl=en