The green squircle you have now seems to be what's displayed when there's a menu entry defined, but the actual PNG file for the icon is missing. (i got it several times when i experimented with my own entries in the application menu.)

there must be something fishy wrt how such icon files disappear. a friend of mine has all the bookmarks he created from the browser displayed as such green squircles. he thought it was the correct behaviour because for him, it was never different.

so what could have happened is that something went wrong during the update, preventing the old icon from being removed completely while the new one is already there.

anyway, I'd just go for the manual solution suggested by Arie. There has to be a *.desktop-file in your ~/.local/share/applications folder that has been changed recenty and, when examine it, lacks lines such as "Name=" (or the name is empty). Delete/move it and the ghost should disappear.