I agree that this should be documented better but looking at their terms of service, the recordings submitted look to be under CC0 [1]. The relevant blurb:

I agree that this should be documented better but looking at their terms of service, the recordings submitted look to be under CC0 [1]. The relevant blurb: Your Contributions and Release of Rights By submitting your recordings, you waive all copyrights and related rights that you may have in them, and you agree to release the recordings to the public under CC-0. This means that you agree to waive all rights to the recordings worldwide under copyright and database law, including moral and publicity rights and all related and neighboring rights. [1] https://voice.mozilla.org/terms https://voice.mozilla.org/terms