When playing back an AV1 video on Windows then the audio can end up being out of sync. This is reproducible in one setup where it works fine in the latest Windows Media Player (Movies & TV) but not in the old Windows Media Player. It also works in VLC as well.

In another case, it reproduces in both the latest Windows Media Player (Movies & TV) and in Qt as well.

In both cases the AV1 codec as provided by Microsoft - https://apps.microsoft.com/store/detail/av1-video-extension/9MVZQVXJBQ9V

This can be reproduced with the QML Media Player example.