Chrome plans to deprecate the U2F interface starting in M95 with warnings, disabling it by default in Spring 2022, and fully removing it in Summer 2022. We supported this legacy API primarily because the Google website required it to register credentials; we will be happy to follow suit.

See their Intent to Deprecate thread:
https://groups.google.com/a/chromium.org/g/blink-dev/c/xHC3AtU_65A
(Note that the dates in the original June 11 mail were pushed out in a later September mail)

Or clearer:
https://developer.chrome.com/blog/deps-rems-95/#deprecate-u2f-api-cryptotoken

we should watch to make sure they don't slip further as we get closer to the cut-off dates.

We will do this in two steps:

1. change the security.webauth.u2f pref to false when they have disabled it (Spring)
2. remove the code once they've fully removed it (after August 2022)

Chrome has fully deleted the U2F API with Chrome 109 (currently in Beta: https://chromiumdash.appspot.com/commit/c86cc6503c9944784099b0d540d3e68bc3bb1f6f).

https://hg.mozilla.org/mozilla-central/rev/9acbf3389238