It’s disabled by default, but I had no idea this was added.
Firefox mobile users started noticing something peculiar this week when sharing links to WhatsApp. After hitting that share button, their messages were getting an unexpected tagline: “Sent from Firefox 🦊” with a direct link to the Mozilla app store listing.
The feature appeared quietly, with no fanfare or announcement from Mozilla.
https://piunikaweb.com/2025/11/26/sent-from-firefox-whatsapp-share-signature/
For me, it was opt in, turned off by default. Apparently it’s turned on if you opt in to studies, but I definitely never do.
Interesting, I was enrolled in a bunch of stuff on Android, but off on iOS.
(was)