On 2025-02-05 Trakt performed maintenance.
If you were using SeriesGuide between 2025-02-05T21:35:00Z→2025-02-05T22:19:00Z and marked episodes watched or did other things that are sent to Trakt, this was not saved to your Trakt profile even if there was no error message.
On the next sync, SeriesGuide should revert these episodes or movies to the state on your Trakt account. And you might have to mark them watched, add them to your collection, … again.