I can confirm this bug exists for SMS factors and not for TOTP factors.
The first time a phone number is enrolled as an SMS factor, Okta reports its status: ‘PENDING_ACTIVATION’. Once that SMS factor is activated, Okta reports its status: ‘ACTIVE’. If that SMS factor is deactivated and the same phone number is re-enrolled, Okta incorrectly reports the SMS factor status: ‘ACTIVE’ when it should be ‘PENDING_ACTIVATION’.
When re-enrolled, a TOTP factor will correctly report its status: ‘PENDING_ACTIVATION’ until the factor is re-activated. Is there some reason why the SMS factor behavior is different?