Management recently rehired some users. Prior to IT reactivating their accounts, they were able to log into Azure AD joined PCs using their previous accounts and passwords. I have confirmed they are deleted in AAD Users. They are NOT able to log into email or other apps, but are able to access PC.
We have disabled cached login via Registry, but the issue seems to persist.
We do use AADDS, but in the Admin center, their accounts show to have been deleted.