This seems to be happening with every Apple TV+ show I watch. Examples are Servant, Schmigadoon, Mythic Quest, The Morning Show, and Foundation. The shows come out on Fridays at midnight Eastern time, but for some reason, Seriesguide lists them as premiering on Saturdays, so they show up incorrectly on the widget and don’t appear in the unwatched filter correctly when they’re available either. Trakt, TMDB, and TVDB all seem to have the correct info. I wonder if it is perhaps interpreting midnight as 24:00 rather than 0:00, causing the app to think of it as the next day perhaps?
EDIT: I noticed 12:00 AM shows on Hulu show the correct date, such as Only Murders in the Building and Animaniacs, so it wouldn’t be related to the midnight time itself.