Why are so many people suddenly getting panic attacks/super anxious when they smoke?

I’ve been hearing about this more and more. Someone has been smoking daily for years and all of a sudden they get a huge panic attack and feel awful, then they can never smoke again because they keep getting that same reaction. Any ideas about what this is? Why does it randomly “turn” on people?

I’ve had this reaction recently, but it has always relaxed me prior to this. It’s really weird and I can’t really understand why it would happen out of nowhere.