If I look at the calendar, it shows it is still thursday, however, my PC’s and my NAS (on which sonarr is placed), show it is friday (which is correct).
Sonarr’s UI relies on the time of the client for displaying times, if they’re off by an hour its likely daylight saving time related so doublee check your settings.
I did double check. I live in Belgium, and the date command on the NAS shows the exact right time and timezone.
I rebooted the NAS, and now it’s fine. I guess it was on already for too long, maybe DTS was involved, but date gave a right datetime, but Sonarr had it cached somehow?