oof that's bad. Especially since it appears inside the content pane, since it could very well be a malicious site putting that banner there. If it appeared outside the content pane then at least you could be sure it was from the browser itself.
"There are no plans to decommission Persona. If it fits your needs, please use it. We will support you."
"Update: The persona.org services hosted by Mozilla will be decommissioned on November 30th 2016."