The time (and potentially the date) reverts back to the original time and date that was there, if you try and put in a time that's later than the start time. The end time will change, drifting out by 30 minutes from your desired start time or whatever, but then you need to re-input the start time.
Capacities v1.47.2; none none; Windows v10; Chrome v134.0.6998.88 (WebKit v537.36); Desktop (Electron); 29/04/2025, 08:32:41