That's plain wrong. Sure, if you used Monotype's there will be issues (because they're so litigious), but Google Fonts only hosts open-source fonts so there's no reason to just search the correct font and host that instead (unless you somehow manually tweaked the URL to get Product Sans: that's illegal even if you loaded it from Google's CDNs).

What are the issues? I freaked out for a second because I'm pretty sure I host materialicons font files and css files.

I checked the docs though and it seems like self-hosting is within the license.

Maybe material icons are different or maybe I'm misreading this page.

https://developers.google.com/fonts/docs/material_icons