It does the same thing as laser, it kills the follicle using a burst of heat. Even laser is in some sense temporary and you’ll have regrowth, but in either case that process takes months and it’s very gradual, it’s why laser clinics say you need to perform maintenance.

I stopped doing IPL for nearly year and I can count the numbers of chest hairs that came back on my hands. I had a similar experience when COVID lockdowns interrupted my facial laser sessions for a couple of months, except that grew back faster. I think a large part of it is related to growth phases though, as in you’ve gotta kill the follicle at the right time for it to stay dead or something, I’m no expert.