Update: thanks for the input all. I found her dead this morning – I think it was a molting issue as others pointed out it looked like her carapace had partially lifted.
I could only see one or two eggs still under her tail, hopefully the others were able to hatch in time!
I’ve noticed something similar with one of Mine. She’s a Black Rose and super opaque.
After She molts She’s entirely black for a bit and super Shiny like your Red lady on Pic 2. After that She has her Rusty/Blue Dorsal stripe Fade in and will stay like that until her Next molt.
It could be that she’s getting older as well & also possible berried mama stress along side the above!
It’s worth noting they have a short lifespan. I have a community in a 20 gal that sustains themselves. I have so many it’s hard to see the same one twice but I do notice when I have to remove bodies, they are usually larger females that I assume have or were able to have babies.
MowMyLawn69 
Let’s see you birth 40 children and come out looking in shape.
Should be OK.
Buff ass shrimp 😂
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The head looks kinda detached from the tail from the first photo maybe a molting issue
Update: thanks for the input all. I found her dead this morning – I think it was a molting issue as others pointed out it looked like her carapace had partially lifted.
I could only see one or two eggs still under her tail, hopefully the others were able to hatch in time!
I’m glad you asked this. I just noticed one of my red females had lost color this morning. Shes acting normal but just looks strange.
I’ve noticed something similar with one of Mine. She’s a Black Rose and super opaque.
After She molts She’s entirely black for a bit and super Shiny like your Red lady on Pic 2. After that She has her Rusty/Blue Dorsal stripe Fade in and will stay like that until her Next molt.
It could be that she’s getting older as well & also possible berried mama stress along side the above!
I should add, there are about 15 other shrimp in the tank and they’re all perfectly fine.
It’s worth noting they have a short lifespan. I have a community in a 20 gal that sustains themselves. I have so many it’s hard to see the same one twice but I do notice when I have to remove bodies, they are usually larger females that I assume have or were able to have babies.
Is she old?
It’s developing a messy racing stripe. Very common old shrimp behavior