Sunshine unable to use HW encoding

bazzite@bazzite:~$ ffmpeg -hide_banner -f lavfi -i testsrc2 -t 3 -c:v h264_nvenc -f null -
Input #0, lavfi, from 'testsrc2':
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: wrapped_avframe, yuv420p, 320x240 [SAR 1:1 DAR 4:3], 25 fps, 25 tbr, 25 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (wrapped_avframe (native) -> h264 (h264_nvenc))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
  Metadata:
    encoder         : Lavf61.7.100
  Stream #0:0: Video: h264 (Main), yuv420p(tv, progressive), 320x240 [SAR 1:1 DAR 4:3], q=2-31, 2000 kb/s, 25 fps, 25 tbn
      Metadata:
        encoder         : Lavc61.19.101 h264_nvenc
      Side data:
        cpb: bitrate max/min/avg: 0/0/2000000 buffer size: 4000000 vbv_delay: N/A
[out#0/null @ 0x55cab1acb2c0] video:305KiB audio:0KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown
frame=   75 fps=0.0 q=11.0 Lsize=N/A time=00:00:02.88 bitrate=N/A speed=28.9x