Why is a late meal showing on a different day?

A meal's diary day follows the meal time in your profile's time zone and day-start setting. Midnight is the default boundary. A later start can suit night shifts. The entry keeps that diary day rather than changing whenever your phone's time zone changes.

Open the entry to correct its day or time if needed. Changing the day boundary or confirming a new time zone does not move past entries automatically. Check a gallery photo's meal time before saving too: it may refer to when the photo was taken rather than when you uploaded it.