Co-Op Loot Sharing bug?

I play with two friends who are both on PlayStation. We run bosses together and try to stack them up so we can do a bunch at once. I started to notice that they both consistently get good drops, while I barely get any rares. At first, I thought I was just really unlucky but now I’m not so sure.

I’ve done around 10 Breach bosses, a few Audience with the Kings, and about 10 Arbiter of Ash fights, and I’ve only gotten maybe 2 or 3 rare items in total. I did a run with just one of them, and they got three unique items while I only got a single rare.

When I run bosses solo, I get way more loot. So, I’m starting to wonder if this is a bug or just a poor loot-sharing system. Either way, it’s made me stop running bosses with them, because it’s a lot more work for barely any reward.