Embedding artwork into mp4 files writes to stream 0, shifting the video track to stream 1

[bohning]

When I write artwork to an mp4 with mutagen via

tags["covr"] = [mutagen.mp4.MP4Cover(image.read_bytes(), imageformat=mutagen.mp4.MP4Cover.FORMAT_JPEG)]

the artwork is written to stream 0, shifting the video track to stream 1:

ffprobe mp4_with_embedded_artwork.mp4:

Stream #0:0[0x0]: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 1920x1920 [SAR 1:1 DAR 1:1], 90k tbr, 90k tbn (attached pic)
Stream #0:1[0x1](und): Video: vp9 (Profile 0) (vp09 / 0x39307076), yuv420p(tv, bt709), 1920x1080, 1730 kb/s, 59.95 fps, 59.94 tbr, 1k tbn (default)

ffprobe mp4_without_embedded_artwork.mp4:

Stream #0:0[0x1](und): Video: vp9 (Profile 0) (vp09 / 0x39307076), yuv420p(tv, bt709), 1920x1080, 1730 kb/s, 59.95 fps, 59.94 tbr, 1k tbn (default)

Would it be possible/does it make more sense to write the artwork to stream 1, or rather to the first unused stream?