With grouped search results enabled, it is often the case that I will see multiple results from one site matching my query and then decide to narrow the search to just that website. To do this, I typically use the hamburger icon displayed next to search results to open the submenu containing the "More results from this site" option. However, this method requires multiple clicks and mouse movements to navigate what is a relatively small submenu.
My suggestion is to add a dedicated UI button for the "More results from this site" feature, possibly displayed next to the existing "Adjust website ranking" button, which would be helpful for users who use this feature frequently.
Detailed above.
