Agree that's odd. I initially thought they'd delayed AV1 integration to match the VVC timeline but it seems the QC engineers are just generally slower than the ones working at Mediatek...
AFAIK, the VVC Decoder in Mediatek are for TV only, not Mobile. So the power usage is quite different. But I did expect Qualcomm to have VVC since they promised it in 2020 and 2021.