From your description and the photos, I think the darker color is completely normal. Many Easter Eggers hatch with lighter colored legs (with a darker wash) that turn to slate/blue/green during the first few weeks. Purebred splash Ameraucaunas as well as splash Easter eggers are often born with bright orange legs that gradually turn slate-colored.It’s mainly yellow but there is darker up higher on the other leg (higher up then on the bad leg…and I don’t recall either of the legs having darkness when she first came…so I’m not sure what to think either
That is possible, but it is also possible the feathers are being rubbed out if she is spending an excessive amount of time resting on her breast/belly due to being immobile. When older/bigger birds are immobilized, it is recommended to make a sling or chicken chair to prevent breast blisters from developing.And I noticed she’s missing belly feathers - like a broody hen might….wondering if her bad foot is snagging on the belly feathers and pulling them out because she always has feathers and fluff stuck to her foot when I clean it.
I see some separation beginning to develop between live and dead tissue, but it may still take some time before the foot comes off. With older birds, it usually takes approximately 6 weeks after the initial injury before auto-amputation completes, sometimes a little less and sometimes a lot longer. But the average time frame may not apply to your chick since she is so young. Time will tell; that's for sure.