And that's where they are not banned. Many pages simply won't load at all in the PRC because someone thought a Google analytics tracker or a hosted library should load before the content (which then never does).
Google Fonts also isn’t blocked but I recall it being hit-and-miss in terms of responsiveness when I was working on a website that targeted Chinese audience a few years ago. However, I just tried resolving fonts.googleapis.com and fonts.gstatic.com on a Chinese server of mine, and they both resolve to a couple of Beijing IP addresses belonging to AS24424 Beijing Gu Xiang Information Technology Co. Ltd., so it’s probably very much usable now.
I do occasional web dev from within China and had to eliminate external references to get manageable page load times. At least from where I work pulling in practically anything from outside the Great Firewall will have a high probability of killing page load time. Anything hosted by Google in particular will often have you staring at your screen for 30 seconds.