To receive a lot of criticism or judgment. Because I'm in a family full of surgeons, I get a lot of flak for my career in the arts.
get/take (the) ˈflak (for something)(informal) receive severe criticism: He’s taken a lot of flak for his unpopular decisions. ♢ Why do I always get the flak when something goes wrong around here?
Flak is bullets from guns on the ground that are shooting at enemy aircraft.