Macbook Pro M1 garbled audio via USB-C

New Macbook Pro M1 16" from Dec 2021

The audio from the internal speakers is always fine. But sometimes audio through the USB-C connection to a set of external speakers becomes completely garbled.

I've confirmed that the speakers are fine, and the USB-C cord is fine. This issue is definitely an audio-out issue.

This issue appears only after the laptop has gone to sleep, without a full reboot, several times. Only thereafter, when plugging into the USB-C connection, does the audio suddenly get wonky.

If it helps, corresponding video also gets crazily jerky. It's like the entire playback mechanism (whether only audio or audio+video) is completely wrecked.

Restarting the machine fixes the problem.

Any ideas???