The good news is that (other than the pain) it is completely harmless.
The way it always felt to me is like someone wrapped a small wire around something tender in my chest, and if I tried to breathe or straighten my posture, they would yank on it. I’d get it anywhere from a couple times a week to once a month. Then one day in my mid-30s it just stopped.
From what I understand this is relatively common. I was so grateful for the person on reddit who dropped this nugget of wisdom several years ago. It was nice to know I wasn’t dying or whatever.
I haven’t had it in so many years, but I eventually got to the point where I’d just take a deep breath and it would seem to pop away. It would hurt, but then it would stop.
It’s more common in young adults and children, and I’m approaching middle age here unfortunately, but the upside is no more precordial catch.