Mozilla/Firefox is my browser. Lately, every time I am on a website where I need to open a pdf document, like a bank statement I want to download, a pop-up appears that advises me to sign on the dotted line or anywhere and shows a little pen writing something. Underneath is this sentence: "Draw, type or upload your signature, then place it exactly where you want. Save your go-to signature for next time."

Where did that come from? It blocks my view of the document and if i try to capture it in a "screenshot" nothing appears. Is this a Mozilla/Firefox thing or a (Acrobat) pdf thing? And what can I do to stop it?