Replicate the steps in another browser and get to the same point. Then right click on the image and see where it's coming from. An add-on or ETP could be blocking something which is why a full browser screenshot would be more helpful. Try turning off ETP. see screenshot Did you try with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#search If you're running Windows Pro version, I would test in the Sandbox to confirm. https://www.howtogeek.com/399290/how-to-use-windows-10s-new-sandbox-to-safely-test-apps/