Ah Jeff, you are raising some thoughts that may lead to a solution and more questions.
I am monitoring the sync the same as I have for years, headphones out of the computer, and watching the record monitor.
If I export it synced (by being out sync) it works as it should on MOST platforms, which is really bizarre. There seems to be a 25% chance it will appear out of sync depending on if you are watching on mobile or desktop.
Opening a single clip in premiere has the audio of a camera track out of sync with itself. In VLC, it appears to work normally.
It’s probably the oddest issue I’ve ever had.