Old melanotan tan left pale spots - anyone else?

Tbh i'm five months into tirzepatide and down 28 lb, and I've been taking monthly photos of my skin because I'm pale and have a lot of freckles. A few summers before starting, I tried melanotan for about six weeks. It gave me a decent tan but also left two pale patches on my upper arm and one near my collarbone. They faded to where I barely noticed them. Lately, though, those same spots look lighter again, especially after yard work in short sleeves. My dermatologist said pigment can be uneven and didn't seem concerned, but I'm curious whether anyone else with past melanotan use has seen old hypopigmentation get more obvious during weight loss or more sun exposure. I'm not looking for dosing help - just trying to compare notes. Did yours stay the same, fade, or shift over time?