red rili shrimp

I have a 5.5 shrimp tank and for the past week or two, every other day I notice a dead shrimp in the morning. Doesn't seem to matter if it's an adult or juvenile, or what coloration. I have about 10 red rilis, 5 orange cherry, and 5 blue velvet. It's a planted tank with pearl weed, java moss...

So a few days ago I noticed my shrimp has some yellowing under his shell. At first my thought was it’s the fish food but after looking at it I guess that’s not possible because of where it is? Maybe this is a silly question but I just want to make sure he is ok and doesn’t have a disease.