Yes. All machines are joined to the local AD and none are hybrid joined. However they do have linked accounts on a 'Work or School' tenant. Using their Entra ID (or 365 UPN, e-mail address, whatever you want to call it) as their primary AD login allows more seamless connectivity with Azure, including to the point of ODBC using refresh tokens properly and preventing a login request every hour (because ODBC cannot action a refresh token request without the UPN being in place).
Simply, if their UPN is not listed under the account section of AD users and computers, ODBC will request that they log in every hour.
They still have a linked account that works under almost every other circumstance, though, as most other integrations use the browser cached credentials.
