There's two things to this. One is an option usually called "smooth scrolling" which was historically disabled in Firefox or Chrome (and it was really annoying)

There's two things to this. One is an option usually called "smooth scrolling" which was historically disabled in Firefox or Chrome (and it was really annoying). It was an on/off switch that either animated the movement between two points in page or it just jumped. I believe all browsers have this enabled now. The second issue, what you are probably referring to is how the page is animated between those two points. Firefox now uses something old Opera used to have, a really gradual scroll. All chromium-based browser I just tried have this rather jumpy scroll. It's different, but it is not nearly as bad as it used to be in FF. In short, I don't know, but "smooth scrolling" is something you might want to search for.