Firefox, sharing a link in Android

When I tap to share a link from Firefox (private window) in my Android phone, for example into whatsapp, I get something like this:
+++·····················
https://www.huffingtonpost.es/global/analistas-confirman-putin-quiere-guerra-unica-sorprendente-razon.html
Enviado desde Firefox 🦊 https://mzl.la/3D860mB
·····················++-
The second link is a commercial from Firefox. It expands to a link to install Firefox (not always the same link: in this Linux machine, it thinks I'm using an Apple: <https://apps.apple.com/us/app/firefox-private-web-browser/id989804926>)
This is happening maybe since a month ago.
Every time I share a link, I have to delete that part manually. Is there a setting?
--
Cheers, Carlos.