* It seems Google Location Services has been the default location provider since a long long time ago (probably since before the Mozilla service existed).
* It seems like Firefox uses system APIs (and only then falls back to GLS): https://bugzilla.mozilla.org/show_bug.cgi?id=1512161
* It seems at one point the plan was to switch to MLS completely, but was reverted before hitting release: https://bugzilla.mozilla.org/show_bug.cgi?id=1216662
* And it seems currently Firefox is using MLS on Early Beta / Nightly, and comparing results to GLS: https://searchfox.org/mozilla-central/rev/d6d8ea296d3560615f... / https://bugzilla.mozilla.org/show_bug.cgi?id=1637402