Hi,
Service accounts and service principals, such as the Microsoft Entra Connect Sync Account. Service accounts are non-interactive accounts that aren't tied to any particular user. They're normally used by back-end services allowing programmatic access to applications, but are also used to sign in to systems for administrative purposes. Service accounts like these should be excluded since MFA can't be completed programmatically. Calls made by service principals won't be blocked by Conditional Access policies scoped to users. Use Conditional Access for workload identities to define policies targeting service principals.
In summary, MFA not affect service account.
I send you the link about this info:
Please, if the answer is validate for you, click in correct answer