The friend who only knew you during a crisis may mistake recovery for distance.

Someone who met you in a crisis knew a particular version of you. When you recover, the intensity that defined the friendship goes with it, and they can experience that as being pushed away rather than as you getting better. The closeness was real and it was partly built on conditions that have now ended.

If you are the one recovering, say what is happening rather than letting the reduced contact speak for itself. And if you are the friend, resist reading recovery as rejection. It may mean the friendship has to find a second basis, and that is worth attempting explicitly rather than waiting to see whether it happens.