> This sounds like a very weird edge case and it's very easy to say this sort of statement in retrospect

As someone who works on embedded devices with a lot of experience with Hardware-in-the-loop testing, this is 100% a QA oversight.

The way this feature is implemented screams "test it from boot to reboot". I wouldn't pick too much on a small company doing some basic BSP/application work for some HMI device or something like that, but this is the richest company in the world with major funds/infrastructure to be better than this.