Amulet lowering my DPS (display bug)

Hello Guys

FINAL EDIT : sorry it's a display bug (I guess ?)
------> I moved a bit, took a waypoint, my dps became 4600
------> then I took back my amulet : 4400
------> Then i put it back : 3900
SORRY for this "useless" post

Coming to you because I don't know if I'm facing a real bug or If I'm dumb

Attention : both amulet I'm goingto speak come from the NPC that gave you random rarity item during the campaign.

Here are my stats without any amulet :


Here are my stats with the first amulet :



Here are my stats with the second one :




I would just like to understand why the dps is going low, any idea ?

EDIT : same is happening with the rings

Thanks for future answers !