To access rating information on mobile you need to go go to Now playing screen, click the three dots to see if the song has a rating at all. Understandably you aim for cleaner interface, but that is really cumbersome and frustrating when you wish to rate a song only to see it has already a rating.
It would be great if track rating would be visible in more places like playlists (desktop) as well as now playing screen (mobile) for information and quicker access. For comparison, see how Google Play Music (RIP) used to handle it:
PS Arguably, thumbs up/thumbs down is a more intuitive and laconic rating system which I would be overjoyed to see on Plex (maybe as an option), but that’s an entirely different topic.