[0942v8653]

Google Fonts does see the page you are on, in the `Referer` header. According to mitmproxy:

    host:              fonts.googleapis.com
    Connection:        keep-alive
    Proxy-Connection:  keep-alive
    Accept:            text/css,*/*;q=0.1
    User-Agent:        Mozilla/5.0 (iPhone; CPU iPhone OS 9_3_1 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Version/9.0 Mobile/13E238 Safari/601.1
    Accept-Language:   en-us
    Referer:           https://blog.filippo.io/self-host-analytics/
    Accept-Encoding:   gzip, deflate

(I agree with the rest of your comment; the best thing to do is host the fonts yourself.)

[ocdtrekkie]

And it does appear Google just blankets this into it's general API terms of use that they can "use submitted data" in accordance with their general privacy policies. So yeah, I guess they can use it as part of their tracking. :/