Guardian project references proprietary google WebAuthN lib in Firefox?

A common note at the end of f-droid repos states any non-free components.
The guardian project’s f-droid repo states the TBB has one such issue.
Guardian Project

“About the Anti-Features In order to support WebAuthn, Firefox includes a proprietary Google library. Tor Browser inherited this change.”
I was not able to find any reference to this on Mozilla’s site, bug reports, etc.
I was also not able to find any reference to this on the Tor Project’s gitlab issues.
I saw that TBB disabled webauthn for a while, but now has it enabled.
Is Mozilla/Firefox really including a proprietary blob library now?
Or, is the inclusion more benign in the form of an iffy, but still open source licensed library.