There is no general link between FAI and shoulder impingement, meaning one does not cause the other.

The history of the shoulder impingement diagnosis is helpful to study, however. It started as a surgeon's theory and became accepted as fact without ample evidence. After many decades and thousands of unnecessary surgeries, research showed that the theory lacked any strong evidence. More importantly, the surgery was shown to be no better than a fake surgery when subjected to independent and rigorous examination.

FAI is a diagnosis invented in the late 90s and early 00s. It appears to be following a very similar trajectory.

If you have shoulder impingement, this video may be helpful:

If you are having shoulder issues, I would recommend you check out these 2 options: https://uprighthealth.com/shoulder-fix and https://www.gotrom.com/super-shoulders-bundle

Both have slightly different focuses but either will be helpful for shoulders!