This happens to me all over the board, rpi3, rpi4, different power cables and sources. Doesn't matter. It is not a power issue. Streams do get interrupted and only the audio returns. It started after the big update which is called Matrix. Leia did not have this problem.
I have had the same experience. LE 9.2.7 and LE 9.2.8 are rock solid with video and audio playback on my rpi2/3/3B+ computers. Anytime there is a disruption in the stream then both the video and audio pause. When the stream restarts then both video and audio resume.
This is not the case with LE 10+ and LE 11+.
I have tried new installs of each official release of LE 10 and LE 11. Whenever there is a disruption in the stream then the video either becomes a static image or goes black. When the stream resumes the audio continues and the video remains stuck. I have a network switch nearby where I can confirm from the blinking lights that the stream is continuing as well.
This is a significant problem that makes the newer versions of LE 10+ and LE 11+ unusable for me.