Is the difference linked to the hardware versions 2 vs. 3? voltasandjolts, what hardware version does your scope have?
v2
Very odd then. So the key difference of 148 bytes vs 388 bytes is not tied to hardware version 2 vs 3, nor apparently to a difference in FW or Android build. I assume then that the header contains an indicator to the app what size the key is. I wonder if it's a regional thing, maybe a different crypto algorithm is used in different parts of the world?
Let's see (assuming everyone's country is set correctly):
ebastler: Germany, HW3, 388 byte key
voltsandjolts: UK, HW2, 388 byte key
bosav: Netherlands, HW2, 148 byte key
me: US, HW2, 148 byte key
Nope, not seeing an obvious pattern there in terms of NA vs Europe or EU vs non-EU.