Portal users can view the case's account because of implicit sharing which happens because we create case apex sharing records for these users. When we remove case apex sharing the users should stop have access to the case's account but the implicit sharing of the account stays. Even if the user doesn't have access to any of the account's cases anymore the implicit account sharing the record for that user stays.
The implicit sharing is not being automatically removed for some reason.
Anyone ever came across this problem? What is the root cause? How can I fix it?