EntraID SCIM does not check group membership

We have a SCIM endpoint where all group assignments are no longer available due to an error. If we now want to force a group to be resynchronized, EntraId always reports that the user is already a member of this group, although he is not a member of the group on the other side. According to the logs, EntraId does not check whether the membership exists on the partner environment, as described in the Microsoft specification. What must be set so that this check is carried out?

A complete synch would solve the problem, but we are of the opinion that Entra should still check the membership of the group.