I feel so embarrassed to admit this but I think I have installed a dodgy extension to my MS Edge browser (mac). I twigged when I saw a suspicious looking DOM element in inspect mode today, and turned off all extensions, then re-enabled until I found the extension doing it.
The link to this extension on the Edge add-on store is:
I have started looking at the JS code and it looks suss. So is it true that this is not a sanctioned Edge port of the Session Buddy chrome extension? I have reported it to Microsoft as possibly dodgy, and I sent an email to Session Buddy via the contact page. But I thought it should go on this forum as well.