From the post:
In 2023, a significant portion of Firefox downloads came from unknown sources. We believe many of them came from 3rd party websites that let you download Firefox. While some websites are okay, others can put you at risk of downloading an old version or a build with the wrong locale, leading to security risks, a bad user experience, or even malicious installations.
Help the Firefox team to uncover this mystery by taking part in the Firefox 3rd-party installer campaign 3!
There will be swag, and you’ll be featured in our blog if you manage to report 10 valid reports. So don’t forget to invite your friends too!
Have any questions about this campaign? Join us on Matrix or watch the recording of our community call with Romain Testard, Principal Product Manager at Mozilla.
Please also help spread the word about this campaign by sharing this on your social media.
Keep on rocking the helpful web,
Kiki & Konstantina
Well, almost every Linux distro includes Firefox. Maybe that's where these downloads are coming from?