We have recently experienced a security incident that may potentially involve your Plex account information. We believe the actual impact of this incident is limited; however, action is required from you to ensure your account remains secure. What happened An unauthorized third party accessed a limited subset of customer data from one of our databases. While we quickly contained the incident, information that was accessed included emails, usernames, securely hashed passwords and authentication ...
I had something similar when I used XMBC (I think it’s called kody now) and it seems it was because there was some confusion with the scrapper to imdb and it needed some manual override file. You had to create a .nfo file or something like that, that told the scrapper the right imdb number or other exact identifier for it. I wouldn’t be surprised if the people at plex have some way to know of all the custom fixes people do and with that, when you have some issue recognizing some content, they can figure out what most people do.
I would be surprised if jellyfin has any way to to know what the users are doing so that wouldn’t work