One of the hassles that comes with being a G Suite admin is making sure everything is secure, which can sometimes fall outside of your control. Employees are notoriously one of the weakest links in enterprise security, so it's good to have multiple two-factor authentication methods to cover for weak passwords and the like. One of the more common methods for 2FA is SMS, but due to notable failings in its security, Google is offering admins the option to completely disable it for their domains.
Starting today, both Rapid Release and Scheduled Release domains will see a gradual rollout adding this option to the admin panel. Users who rely solely on SMS 2FA will be locked out of their accounts if another method is not added before the admin disables the option, so be aware of that.
If you are worried about employees being locked out, this option will not be enabled by default, so you'll have time to get everyone switched over to security key-based or app-based authentication methods. All editions of G Suite are eligible and should see it pop up within the next 15 days.