I am on a Mac using DoP for DSD output.
This is common effect with many DACs when using DoP. USB interface should delay data stream enough that unmute happens about 100 ms after DSD data has been detected, and mute 100 ms before DSD data ends.
Delaying unmute at start is easier, but really the only way to do proper muting at stop is to have enough buffer/delay in the USB interface so that it can see "ahead of the time".
This is just one of the many down sides of DoP.