When media is playing with loop set to MediaPlayer.Infinite, there is no way to stop looping the video immediately. Setting a value of 0 does nothing (as documented), and setting a value of 1 causes the video to loop once before stopping.

This is required to toggle between looping media continuously and not looping at all.

This appears to have previously worked in Qt 5, and if I had to guess, the property is probably decremented when the video starts, such that an initial value of 1 only plays the video once, but changing the value during playback to 1 means it reaches the end with a loop remaining and it loops again.