Server Version#: 1.25.5.5492
Player Version#: 1.40.1.2823
Playing back H.265 10bit video (direct stream without transcoding) with Plex for Windows gives quite noticeable artifacting in highly saturated reds, for example red neon signs, red text or blood. 8bit and 12bit H.265 do not have this issue.
Also the artifacting does not accur when playing back the same 10bit H.265 using VLC, the bitrate seams to be irrelevant.
This issue only accurs when using hardware decoding, software decoding works fine (VLC plays the file fine with both hardware and software decoding).
I encountered the exact same issue with VLC about 4 years ago where it also accured only with hardware decoding and H.265 10bit material, however they seem to have fixed it in the last couple of years, however I cant find it anywhere in the changelogs, but I highly suspect the issue might be related.
Here are a couple of example screenshots, both are the exact same H.265 10bit file and both are using hardware decoding on the same hardware.
The artifacting ones on the top are Plex for Windows and the ones below are VLC.
