MacBook Pro can't find startup disk--but only sometimes
Most of the time my MacBook Pro (2017, no touch bar, Big Sur) works just fine, but when I move it from place to place it sometimes then won't start up and gives me the error screen with a folder with a question mark inside it. I then have to reboot it a bunch of times, and I end up moving it around and jiggling it (go ahead and scold me), and then it works again.
I know that error means that it can't find a disk to start up with. The fact that this only happens sometimes makes me think it's a hardware issue, but I can't be sure. I tried the recommended fixes (e.g. resetting NVRAM) but am stuck. It also occasionally happens when I haven't moved the Mac. It's only shut down once or twice while I've been using it, but sometimes when it goes to sleep it, it won't come back on.
Does anybody know what might be going on?
Here is a problem report from one of the many times it's shut down:
MacBook Pro 13″, macOS 10.12