if i know there are foamers nearby i try to find a full cover instead of an half cover. most of the time theyll just foam you on the spot and you're still safe from the others since theres a full cover.
alternatively it's better to just kill them quick or blow up their tank quick.
no issues really.
they are only an issue if youre lacking awareness i think ; which is good. that should be punished.
They are super annoying, to be sure, but like said, it's all part of the crafted need for battlefield awareness. Pay attention, prioritize targets, and don't get caught in poor positions. Talents and such can greatly help, too. If you don't normally have Wascally, maybe get a sidearm with it just for True Sons missions.
Of course, none of this helps when you do get caught out and die, making you want to smash your controller, but there are a LOT of things in this game that can ruin your day fast with a missed change of circumstances.