Updated my Manjaro installation this afternoon.  Before the update (running Emby 4.7.14), hardware transcoding was flawless.  After the update (Emby 4.8.1.0), media that needs transcoding shows a solid color screen.  A movie I tested shows a solid gray.  A tv show shows a solid pink.  No rhyme or reason for the color choice, but it's consistent.  Audio of the media is audible.  Switching hardware transcoding off and using CPU works fine, indicating to me that ffmpeg is working as expected.