I bought a Surface Laptop 3 15" AMD Ryzen 16GB in January 2020. I have the same issue with audio getting ahead of the video after a while. I've seen it happen with streaming and local videos on the hard drive. After restarting my PC, it sometimes will not occur for a while, but eventually it will happen and get worse. Heavy loading such as copying files from the hard drive to the network drive seems to immediately trigger the problem, but I've seen it happen under almost no load.
I used to have the Black Screen of Death after closing and reopening my lid. Now it rarely happens after I turn off most power savings features. That is also ultra annoying. I didn't imagine I'd be having these issues with a premium, supposedly mature Microsoft laptop.
I've tried many things (update drivers, different players, different videos, streaming, local files, no external monitor, light load, heavy load) to try to narrow down the issue. Now I found that if the audio and video gets out of sync, I can temporarily resync by closing and opening the lid. I wonder if that temporarily fixes it for others. If so, maybe Microsoft will read this and this info will help them fix whatever is causing this issue.
Edit: It seems switching from laptop to monitor speakers also resyncs temporarily.