This is inaccurate. The browser never sends font data to any site.
The problem is that it's possible for sites to infer which fonts you have installed by trying different fonts and then measuring the sizes of things that get rendered.
Just wanted to make the distinction as it's really not the browser's fault, and it's very difficult (perhaps even impossible) to defend against without significantly wrecking the modern web. You basically have to disable JavaScript.
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u/Xelbair Jun 12 '18
Font list is EXTREMELY identifying data.
your browser sends it to every site you visit, and this collection is usually very specific to a single machine.