This is just a theory based on a very short playtime but…
I believe that any relics that boost Luck are breaking the event special drops.
I was farming the Force Troopers for a legendary class mod. I have a Lucky Snowdrift relic that boosts my Luck by 12.67 (also the Snowdrift which increases slide speed, and shock damage/electrocute chance boosts which are great for my Amara, this is one of the best relics I have including legendary). I equipped it for my farms thinking it would help. I killed these guys probably about 15-20 times and not only didn’t get a single legendary class mod, but did not even get a single class mod PERIOD. In fact, I got exactly 1 legendary item (Recharger shield, but it wasn’t as good as the one I’m using).
I then decided to try farming a few times without the relic just to see how worse the drops may be. To my surprise, they were now dropping at least 2 class mods (not legendary) every run, AND after only about 3 runs I got a legendary Zane class mod (not what I want but still good stuff).
Now this is a very VERY small sample size. I know that maybe it’s just RNG, but it feels like anytime I use a Luck boosting relic during these events, my chances of getting the increased drops actually DECREASES to the point I don’t even get any good drops at all.
Gearbox please look into this. It doesn’t make any sense that my drop rates would be worse with a Luck relic. What strikes me is the part where they don’t drop class mods at all. It’s like night and day, so it seems to me the increased drop chance is actually to class mods universally, and since they can drop legendary gear that means more chance to drop legendary class mods (they may have also increased base legendary drop rate as well, but it doesn’t seem like they specifically put it to “legendary class mods”, instead it’s “class mods” and “legendary” as sort of separate effects).
If anyone else is experiencing this please let me know. I will continue to farm these rare enemies and see if I can gather more uhhh… data (I’m not writing this stuff down LOL) to pinpoint the problem.
EDIT: To be clear, the Luck relic does work normally. When I’m using it I notice a substantial increase in loot drops, particularly legendaries from chests. It’s only when you use the Luck relic for event boosted drops that it seems to break.