The Mapillary app is demanding for mobile devices. Energy hungry hardware like screen, camera, GPS, CPU are busy at the same time and drain the battery.
This energy generates heat in the device and covers and bike/car mounts and protective covers further make it difficult for this heat to compensate into the air.
I have had terrible experiences with the mobile app and warm weather when the app becomes slow, unresponsive, stalls completely or simply crashes. All not mapillarys fault per se, as the OS and device manufacturers throttle speed of the CPU or push a warning when the temperature of camera and CPU are above a threshold. To the user though it is the fault of mapillary. I myself have reported many bugs, some of them turned out to be simply depending on the weather. That's also a strain on the developers, as those bugs due to high outside temperatures aren't easy to reproduce (...especially in Sweden).
Here is an idea how to fix this.
Make picture taking frequency (10 instead of 5 m), resolution (lower), focus (manual infinite focus instead of per-image autofocus), display (dim/off) variable and react to the temperature sensors and battery level dynamically. Show some info: reduced image resolution due to hight temp/low battery.