The massive influx of new ratings could also simply be linked to the fact that the game is included in this month’s humble choice, adding a ton of new players

I’ve seen this news published at a few different places, and IIRC they plan to use already existing exploits. You can read a bunch about what could potentially be used on the grapheneos website, specifically on how the modem and cellular network stack is very highly privileged on android at least, and it is very likely that most cellphones are vulnerable to some kind of code injection via a stingray, for example.