We're limited on what we're able to share in public forums related to specific customer situations.
If you're not already doing the following we recommend the following steps to protect your G Suite account - have more than one super admin - ensure an up-to-date recovery email is in the account profile - ensure an up-to-date recovery phone is in the account profile - ensure account profile is properly updated - use two factor authentication for all users (ideally user security keys) - at a minimum, ensure that your G Suite administrator users are using two factor authentication
Lots more info on G Suite security best practices can be found here: https://support.google.com/a/answer/7587183