I've been in quite a few games now where i've seen that and figured i must have landed in an Apex Mission when i joined. Each time i joined a game that was already in progress so didn't really look what the map/mission/enemy was, i just pressed enter.
Don't know about damage, but i have definitely seen the power cells/ammo thing and you don't replenish ammo from the crates either.
While true, that's not...
... well, so far, I have only come up with two workarounds: one is to simply not play - this is no fun, but does keep me from having to deal with the corrupt hosts; the other is to keep a list of names and then do custom squads that avoid them (or stop playing while they seem to be present).
A related problem, though, is wasting boosts if you use them and then find yourself in a hacked mission. It's... frustrating.
