Salesforce is still prompting for a verification code even though MFA is disabled and bypassed through a permission set.

 We had successfully disabled MFA for our Salesforce sandbox and production environments and used a permission set to bypass verification. This approach worked fine for the past two years and we were not prompted for verification codes. However, recently we’ve started receiving a verification code prompt on every login. Does anyone know what change might have caused this, and is there a way to resolve it? Any help would be appreciated. Thank you.