Same issues here, I bought the PS5 as a game system, but also intended to use it as a media hub in the main room since the apps built into the TV are dire (Plex app, LG CX TV).
The PS4 Pro Plex app seemed ok, although it did suffer sometimes with buffering and a lack of support for the newer codecs, I had high hopes that the PS5 version would overcome all of that (after all the PS5 is a beast of hardware!). - Alas no, it buffers like crazy, randomly just gives a black screen and spinning orange circle, it seems a LOT of codecs still aren’t supported, which then causes my NAS to have to try and transcode which it is woefully underpowered to do, especially on the higher quality items.
I could buy another piece of beefy hardware to run the Plex server on so that it could do the transcoding, but this seems like a waste when I’ve already got the PS5 sitting there and it seems it should be able to handle almost anything we care to throw at it.
Are there any plans for an update here?
Is the blocker with Plex, or with Sony?
Should I “sit it out”, or do we abandon the PS5 as a player and find some other route 
