Quick scan, this is going to be dependency hell.
So ffmpeg 7.1 needs libsdl2-dev, which needs libudev-dev, which needs libudev1, and specifially version 252.31-1~deb12u1, but as I already need debian-backports packages for hass core, version 254.16-1 is installed.
But… I think I can disable the SDL feature for this particular use as SDL is used for native video playback so I’m going to recompile the package without support for SDL…