What is this design trend called?

I'm seeing quite a few web applications and websites that look this on the front end. Any ideas its origin or name so I can study it further? The color gradient blend of the buttons, the illustration styles...

https://www.algolia.com/
https://stripe.com/
https://kinsta.com/
https://ionicframework.com/
https://status.im/
https://cssninja.io/
https://tipe.io/
https://lusaxweb.github.io/vuesax/

https://www.sqreen.io/plugins?utm_medium=cpc&utm_source=t.co&utm_campaign=Twitter%20-%20cpc%20-%20Plugin:%20Security%20Hub

https://www.madebyspeak.com/blog/posts/web-design-trends-2018
https://www.b3multimedia.ie/top-10-web-design-trends-for-2018/