This page requests the Pacifico web font from Google's servers
(the stylesheet from fonts.googleapis.com, the font file from
fonts.gstatic.com) and then checks, using several independent
signals, whether the font actually downloaded and rendered.
Browsers or extensions that block, proxy, or locally substitute Google Fonts (for privacy reasons) will make some or all of these checks fail. That is the point of the test: to show whether the remote download succeeded.
Idle.