Thanks a lot for the reply; it works well for the main page of this sub, but as you said targeting the sidebar is more challenging.

I assume there is a difference between the two, but how could I possibly tell?

I’m a user not a developer, the best I can manage is mess with the Fx UI with a little js and css.

Just to be clear, as said above there is no other website that has triggered that notification icon in years. I forgot it existed; and it is concerning that lemmy is overriding a browser’s security setup.