It is not like Qualcomm settles with Apple to get into Apple's cellphones, it is a concession made to make them drop Intel and still pay them royalties after Apple finishes its own modem.

Apple been poaching Qualcomm's top radio engineers for years ...for work in their Chinese RnD centre (no non-compete enforcement there)

I feel like it's the reverse, since the lawsuits really only started on the heels of Apple supposedly sharing secrets with Intel to help develop their baseband tech. The litigation was probably ended because Apple eventually realized that Intel wasn't able to come up with a decent baseband chip that could compete with Qualcomm, much less one that could satisfy quality constraints and volume production across all of Apple's product lines. Apple had to come to a deal with Qualcomm (at the very least, so they can potentially gain access to Qualcomm's IP). Intel either was already planning to throw in the towel or this was the straw that broke the camel's back. With Apple deciding to stick with Qualcomm (or their own homegrown chip), there's no potential market for an Intel 5G modem and no point in throwing more money after bad.