Home Assistant corrects transit departure readings around midnight and across timezones. Night routes whose services all run after midnight stop incorrectly reporting that no departures remain, while tomorrow’s first journey receives tomorrow’s date instead of a timestamp in the past.
The GTFS connection also selects the next departure using the transit agency’s timezone. Comparing against Home Assistant’s own timezone could otherwise choose a bus or train that had already left.
Owners who used the offset setting specifically to compensate for a timezone difference need to remove that workaround when adopting the correction; keeping it applies the adjustment twice. Other uses of the offset are separate from that timezone workaround.