SOLVED: Playback doesn't work right anymore

[TheDreadPirate]

AMF should work as long as you configure it correctly. For the list of codec boxes check

MPEG2
VC1
H264
VP9
HEVC

But don't enable HEVC encoding, "Allow encoding in HEVC format".

On your TV, set the audio output setting in the Jellyfin app to "downmix to stereo". If the issue is what I think it is, this is a bug in the android TV app and setting the audio output to downmix is a workaround.