To be fair, it's common practice to measure marketing campaign effectiveness. Mozilla doesn't hide that they share data to "Measure and support our marketing"
"Campaign and Referral Data: This helps Mozilla understand the effectiveness of our marketing campaigns."
"On iOS and Android: Firefox by default sends mobile campaign data to Adjust, our analytics vendor, which has its own privacy policy. Mobile campaign data includes a Google advertising ID, IP address, timestamp, country, language/locale, operating system, and app version. Read the documentation."