Which method were the first two screens for? Are all methods set the same? What methods specifically is thi happening to, or is it all methods?
The Spotipo is a guest portal, which means it is performing the guest management in a delegated role from Unifi. You can "unlimit" sessions on Spotipo, but they still can't exceed the limits of the Unifi Guest policy.
The expiration is literally, when the guest access granted by the Unifi controller expires.
One very simple (and unlikely) cause could be if the Spotipo and Unifi controller are on separate machines and have unmatched dates. The other cause could be if your guest are actually hitting that 7 day limit and the after hours is just a coincidence.