linux – Why ffmpeg convert adds unwanted mpeg4 stream?

I’m converting a dvd dump with mkv container.
The commandline I use is
./ffmpeg -i "$a" -sws_flags spline+accurate_rnd -map_chapters 0 -map 0:2 -c:v:1 copy -map 0:1 -c:a libopus -b:a 160000 -vbr constrained -packet_loss 1 -fec 1 -map 0:0 -c:v:0 libsvtav1 -preset 4 -crf 34 -svtav1-params profile=main:tune=0:mbr=2530k:enable-variance-boost=1:variance-boost-strength=1:fast-decode=1:scd=1:enable-tf=2:qm-min=7:qm-max=13:enable-qm=1:mbr-overshoot-pct=35:keyint=10s -filter_complex "[0:v]yadif=0,scale=w=1536:h=864:interl=-1" -avoid_negative_ts 1 "/mnt/incus_share/o/${INAME}.mkv"
However it always adds a mpeg4 stream(as target 0:3) converted from source 0:0.
The source has the following maps
0:0 main video h264
0:1 main audio pcm
0:2 coverart (said as video)