Hello, I am using the script suggested by you to deactivate Google Fonts.
I am using Content-Security-Policy on my site and it seems like some script around is still pre-fetching Google Fonts on administrative backend (the post writing/editing page):
<link rel='dns-prefetch' href='//fonts.googleapis.com' />
How can I deactivate it?
this can only be caused by a plugin. Please try to deactivate them once and check again. Afterwards you can activate them one by one to figure out which plugin is using the prefetch.