I logged in in https://stackexchange.com.
I clicked on the inbox (in the top bar) as I had a few notifications. After clicking somewhere else, the inbox count is still shown.
I clicked on the trophy button (in the top bar) as a reputation increase was shown. After clicking somewhere else, the reputation increase is still shown on the trophy.
Generally, the reputation increase and inbox count disappear after clicking on somewhere else. So, I feel this is a bug.
If we reload the page, they disappear.