Almost every single one looks about the same.
Don’t get me wrong, it’s not that I don’t like it because I do. it’s beautiful and minimal, but is it right to give Vercel the credits?
If not, where did it originate from?
The current flat style (also called material or modern design) is a rejection of skeuomorphism or trying to make interfaces that look real. Instead we got lot of flat boxes all lined up with similar text and icons. You can thank/blame Google for making this popular at first. Then, the web frameworks like Angular (first), React, and Vue started shipping components in this style (Twitter Bootstrap, too). Since those frameworks are everywhere, that look is everywhere.