Everyone’s family is dysfunctional in different ways.
In mine, we found it safer to express long pent-up resentments and criticism of each other if a (soon-to-be-embarrassed) third party was present.
For instance, my mother’s hatred of my punk rock outfits only came out when we ran into one of her friends at the mall and she started “joking” about them to her pals, as if I weren’t there.
Criticizing other people is hard. We all develop our own drive-by “butt covering” tactics to pull it off (and get what we want) without (hopefully) getting knocked over by too much blowback.
My family’s broken “telephone” game is one.
The old “mouthwash in the locker” move is another.
What most of them have in common is the cowardly but highly effective “chemical warfare” of life strategies: passive aggression.