It is because they squized all electronics into tiny footprint. As a result, genetated heat can not be vent into air easily. Besides, some microSD cards heat more than others during "write-access". So, if you want to use it intensivelly, may be you should buy a bigger and metal housing one... I used my one in Tesla Model 3 to record sentry videos, it is always hot, sometimes it is disconnected from car's computer. I suspect it is due to heat problem... I will also change to a bigger housing one. Rgds, Cengiz
I think there is something else. At the USB2 output it is inconspicuous, at the USB3 port not only the USB plug gets warm, but the whole case of the Raspi (no matter if there is an SD card inside or not). But thanks for the answer!