PROBABLE SOLUTION - HDMI CABLE
I had this problem since 2021 (Monterey?) but was not always evident. Restarting with the HDMI output hooked up never helped me, but on some setups it just did not happen and the sound was flawless.
I went to the Genius Bar yesterday and although they said they were not tracking this issue, they sat and troubleshot with me using one of their LG monitors with speakers. I used all the different dongles I had tried (Anker x 2, Apple etc) and we tried our best to re create the issue but the sound glitching never happened. The ONLY thing I did not bring was all the HDMI cables I was trying, and I had tried a lot. BUT I had always just been trying old cables that I had in my drawer of 100 HDMI/DVI/VGA cables thinking surely trying lots of different ones would discount the cable....I think I was WRONG. Cables matter for bitrate, we all know this, but I figured surely these were a good cross section, even using the one from my (old) Apple TV or my kids switch.
Then I bought a $2.99 monoprice one from Amazon that is 4k certified. And it solves the issue. On every setup I have, with every dongle I have tried. Even the 8k certified one is only about $10.
So, YMMV, but even when you think you have tried everything, and lots of HDMI cables, maybe buy a new one, and give yourself permission to throw all those old ones out. Good Luck!