Maybe I can add my 2 grains of salt here. (Hypothesis)
As an IT profesional I can tell you this,
they all run on a linux flavor of operating system:Android Customized for Parrot.
Usually very stable but external bad in-out can cause errors that could cause a system crash or reboot.
Example: a bad execution instruction is rejected , somehow goes to the memory module and boom, a protection reset.
These birds are flying computers with memory, cpu, boards etc.
Extreme temperatures, faulty wirings, bad cooling, bad memory, or gps contact , dirt, electromagnetism etc etc. can affect them
dont panic ok, it doesnt happen most of the time. Most likely never. But remember what they really are.
There are ways to check the event managment to see what really occurs in detail. Event extended logging can be set but it is beyond the scope of the topic if you dont know how to access to Operating System.
It will show whether it was a battery Fluctuation or anything else.
OK, Just that time that really upsets our day.....