Earlier quoted context omitted.
> After a few more days it simply ignored the flight mode and connected to get fresh ads. Worrying. "Flight" mode exists for a reason and should not be overridden.
Flight mode exists because the FAA applies unsafe-until-proven-safe methodology to everything flight related (as they should). If flight mode mattered at all planes would be falling out of the sky on the regular, many people just leave their phones on the whole trip. The only reason I turn my phone off is because it wastes a lot of battery as it tries to manage tower hopping the whole time. Planes are getting blasted…
But, more importantly, it puts your phone's radio through an unusual high-power-draw situation that the phone's manufacturer may not have bothered testing for, which can make phone batteries explode that might not have otherwise ever exploded.
Oh, and also, a plane-load of people whose phones are all ranging hogs circuits on a bunch of towers at once (for no productive purpose, since the phones don't have high-enough SNR to actually communicate anything useful with any of the towers they can "see"), so the cellular service providers have politely asked the FAA to get people to not do that.