Plex seems to be randomly & unpredictably falling back to software transcoding for the last day or two... I think it's an HDR thing? (And unfortunately, almost all of my stuff is HDR.)
Manually rolled Plex back to 1.43.0.10492-121068a07 via the .deb, and I'm able to enable HDR Tonemapping again without breaking 11th Gen Intel HW transcoding to SDR Google TV streamers.
So, it looks like v.1.43.1.10540-3972d551c breaks HDR Tonemapping. (I thought I was pulling that it from the Plex apt repo, but it was apparently from the TTeck autoupdate script. So I disabled that.)
https://www.plex.tv/media-server-downloads/?cat=computer&plat=linux








