Here’s my point in this; his, your, my maintenance are all different. Even at the same height and weight.
Your body is amazing at adaptation. Eating 1500cals or 15000cals for an extended period will reset your “maintenance” caloric intake. IE you will neither gain nor lose weight regardless of what a calculator says based on height and weight.
My “maintenance” comes out to something like 3500 cals using a calculator. I’m eating over 6000 and not getting fat. That would be absolutely impossible unless my maintenance was actually near 6k.
Your body will adjust to stimulus. Whether that’s insanely low or high cals is irrelevant (within reason) assuming youre healthy and functioning. This, along with weight gain during a cycle, this and weight loss during a diet, etc require constant adjustment. 500 cals a day deficit or surplus isn’t all from weight gain or loss, it’s a systemic adjustment by your body because it always wants homeostasis.