I see a lot of confusion in the thread as to what could be the culprit, but I don't use most of the software that's being blamed and I have this issue as well. I've been using my M1 MBA (16GB, 1TB) for 1 week, and it's completely frozen 4 times, needing a forced shutdown.
Like I said, I haven't installed any of the software that's being blamed, with the exception of the native Safari. Originally, I used Migration Assistant to set it up, but have since then done a clean reinstall of BigSur. That didn't fix the problem either. It could potentially be the Rosetta emulation of code meant for Intel machines, but that's just a conjecture (like everything else in this thread).
As usual, we have a product that seems to have been poorly tested, and complete radio silence from Apple. Customer support isn't helpful either. I suspect it will be like any other time that hardware is consistently faulty, taking quite some time until it's acknowledged and a repair program is set up. Although, if the issue is software — which is fair since the M1 chips are brand new and it will take a while until they're fully stable —, perhaps an update will fix this.
It's either this or going back to Intel, y'all, so hold on :)