May I ask why you think Cloudflare would have injected that link-tag with this font there?
Please try put Cloudflare into developer mode and check if it still appears.
Because when I removed Cloudflare, then this font also not appear. I double checked in my HTML pandal there are no code includes with this font name or url.
There are no end tag in this stylesheet. But when I add my custom stylesheet, i need to end the stylesheet with /> or </link tag.
But there are only > tag is shown in the end.
Do you have some Cloudflare Add-ons or anything like this installed? Because I don’t know of any regular Cloudflare feature which will add this font before the closing body tag.