Why do I need Plexpass to sync my movie library?

3 days ago I synced a couple of movies to my library without problem, but after the latest update I am not allowed to anymore. Today I need to buy Plexpass. Why?

@Sixtentherabbit said:
3 days ago I synced a couple of movies to my library without problem, but after the latest update I am not allowed to anymore. Today I need to buy Plexpass. Why?

https://support.plex.tv/hc/en-us/articles/201082477-Quick-Guide-to-Mobile-Sync

Mobile Sync is a premium feature available to Plex Pass subscribers