Wallet pushing notifications for flight tickets a day early (and deleting them in the actual flight day!)

I have the issue that my flight tickets on iPhone 15 Pro could be imported, but appeared on the lock screen a day early. Upon boarding, the tickets eventually disappeared from the wallet right when that time was reached.

Using the mails and the QR codes in there still worked of course, but I have no clue how this shift of a day early happened and what caused it. It really jeopardizes the whole function, as today, my ticket for tomorrow just popped up and I know it's going to disappear when I am actually supposed to board. And the flight date is correct and included in the wallet ticket.

Any help to identify the issue at hand and ideally resolving it would be very much appreciated.