Sorry to have to post this but I’ve been falling into this a lot the last few games.
I’m not sure how it works but it consists of building an anti-tank mine below the rallypoint. I destroyed two rally points with assault rifle and the anti-tank mine below the rally point always ended up killing me.
How it is actually an exploit? It sounds like somebody put a mine on their rally as a booby trap, and you set it off by shooting it.
The solution is to be aware of booby traps and destroy the rally from a safe distance, or while lying down prone, or indirectly with explosives from behind cover.
This is not a bug, but a trap for those who want to destroy your point. You lay an AT mine on a rally points, each mine explodes when the object it lies on it is destroyed. An unaware enemy destroys the point at close range, such as a small room, the mine kills him.