The differential of foot color change is neurological (RSD/CRPS) vs. neurological (peripheral neuropathy) vs. vascular (vascular insufficiency vs. DVT).
See https://neckandback.com/conditions/peripheral-neuropathy/
https://neckandback.com/conditions/complex-regional-pain-syndrome-crps-reflex-sympathetic-dystrophy-rsd-causalgia/
You would need a work-up to determine what your cause would be.
Dr. Corenman