I’ve noticed an issue with Plex for iPadOS. The application will sometimes ignore the autoplay setting and play the next episode. After some troubleshooting, it appears that the following occurs:
If you select a new item to play from the media library, Plex will respect the autoplay setting and if you have it disabled, it won’t play the next episode.
If you play something from the bottom bar, Plex will ignore the setting disabling autoplay and will autoplay the next episodes. The bottom bar I am referring to is the one you see if you minimize what is playing. This only seems to occur if the application has sat for a while, so you can’t reproduce by starting something, then pausing and minimizing and restarting.
I have experienced this exact same bug multiple times by following the steps @alinder11 posted above. (Generally it was in the same circumstance too: falling asleep during the episode and then rewatching it.)