>>4985104 (lb)
It's napalm. Kek
>>4984885 (lb)
FOBs operate on around 350 or 433 MHz.
Point to point UHF radio links can get very close to that and render the fobs inoperable (or rather the receivers) from any great range if they are near the source of the transmission.
It's RF though so the cause of the interference could be literally anything. If the source of the transmission is powerful enough at any frequency the front end of the receivers are sensitive to then they won't be able to pick out the carrier of the fob signal.
At some transmission sites , techs have to take special care to park their vehicles in such a way that they can roll them clear or have a manual override system to disengage their vehicle security systems.