Smooth anchor scroll

Hi.

I have a small issue with the smooth links (I don’t know the exact name, I’m far from expert haha) like you have it in this section: https://themes.ishyoboy.com/kopy/theme-overview.

When I’m in my site, and I click in the links, the site doesn’t scroll smoothly. It goes to the section (the anchor), but with a jump. Am I explaining myself?

Can you help me?

Thanks a lot