Had this happen yesterday. We were up 20 and my team ended up losing by 30. We gained 5 kills after the other team went invisible. I have only seen this once and hope to never see it again lol
I'm sure it's a bug on Bungie's end but if it's an exploit teams are using that's bs. Everytime it's happened to me I've been playing against a 4 stack and somebody on our team leaves/disconnects. Could just be coincidence tho.