channel notifications take a long time to disappear

### Description

Element often takes a long time to clear channel notifications. For example, if I receive a message in the channel that is currently focused, but Firefox is not focused, or the Element tab is not focused, it can take up to 10 seconds for it to clear. That is, the `1` badge still shows beside the channel name, and the Favicon still indicates there is an unread message. The time it takes is somewhat variable, and moving the mouse or beginning to type seems to speed it up (though I can't say that definitively).