The company has recently announced that they will be sunsetting some of its features. The company attributes this to how long the app has been around for, which means that over the years it has gained a ton of features that may no longer be used as much as before, so it makes no sense in keeping them around.
According to Plex, the features that are being sunsetted include plugins, “Watch Later”, and cloud sync. The company writes, “We didn’t approach the process lightly; we looked over usage numbers and took into account maintenance costs and general customer satisfaction. In some cases, we have plans for a future in which a better replacement shows up.”
If you haven’t been using those features for a while now, then it probably won’t affect you too much. For those who have, it seems like you’ll have no choice but to get used to it and hope that Plex eventually finds a better alternative that they’ll introduce in future updates.