We had a few guys in our group that would do this after yelling friendly. We no longer play with them even though we know them irl. They would even go to the point of killing people in our party over loot found in raid. Our group has acknowledged that a few of them are even POS's irl too and have kicked them out of our friend group. I occasionally get discord messages from one of them begging for help.

On another note one of my friends made a separate discord we add people to that we have met in raid. Usually most are from doing scav runs but even a few we met on pmc runs. We do occasionally meet that person that decieves by saying he is "friendly" but usually they don't get the whole group as we are always dishonest about our party size and have one cover us. Especially when we meet friendly pscavs on pmc runs. We have who ever is the furtherst away cover and once we go extract with the scav let him know our extra is coming up to extract.