Google ads: Is it safe to use security key or authy

Hello Everyone, i would like to know is it safe to use 1 security or authy to authenticate multiple google ads accounts. i keep getting "confirm its you" and its not possible to get 1 phone for each account. so will it be okay to use a security key or auth for all of my google ads account or it might trigger the suspension?

Using a single Google authenticator app account for multiple Google Ads accounts, nowadays could trigger even circumventing systems suspensions, as the Google authenticator app account would link multiple Google Ads accounts. Google Ads algorithms nowadays sees that as circumventing the systems in order to create and use many Google Ads accounts. (Ofcourse, circumventing systems suspensions also happen due to dozens of other reasons too).
A safe way is to use Hushed app and buy 1 US number (US$5 per month), for each Google (Ads) account. You can add a US number (as 2FA), even to a non-US Google (Ads) account.

Using same number to verify multiple ad accounts is not a good idea. Google Bot can easily identify that all accounts belongs to same owner. Google have very right to suspend the related account if someone violating google ads TOS.

Why dont u add random phone number as 2fa and print out the backup codes?

Yes there is no problem doing that
It has nothing to do with linking accounts together since google auth app can work offline also
so how google will know that all those keys' are from one phone?