When we use a lot of web browser plasmoid it's hardly distinguishable. I do use some for RocketChat instances at work, having the url fav icon as the plasmoid icon would be a great improvement. For web sites not having fav icon, it would be awesome to be able to set a user one as well.
Still present and annoying... Also, in addition, enabling notifications would be a great feature as well.
This is done for Plasma 6 now; see https://invent.kde.org/plasma/kdeplasma-addons/-/merge_requests/407!