You - like me - are using the watchlist as more of a “favorites” list to rewatch content without having to search for it later. The new “sync watch state” feature breaks that function for us. If you have a movie marked as watched in any library across multiple servers, then the watched state will also synchronize with the watchlist, which then removes the “watched” movie.
If you wish to avoid this behavior, disable watch state syncing. I brought up that question specifically in that forum post I linked, and it’s because it does this that I am not going to opt into watch state sync. (Not that I have any use for sync, since I only have my own server)
