Hi there,
Deselecting the variations removes them from requests.
Say, for example, you only include 300, 300 italic and 300 bold.
These 3 are the only font variants that the theme will request from the google font servers.
By default, GeneratePress theme uses “System stack” on the body, meaning it uses what fonts the visitor has installed in its system. Everything else is then set to inherit meaning it inherits the settings set on body.
Although, if you decide to select anything except “System Stack”(in your case, Roboto), the selected font adds all the variants by default. You may remove the variants you don’t need.
A wise man once said:
"Have you cleared your cache?"