When a tab is 'sleeping' or freeze dried (or whatever it's referred to as), the favicon and table title dim to indicate this to the user. But that dimming effect doesn't apply to emojis if there's an emoji in the tab title! I attached a screenshot (I also zoomed in and put a red rectangle around the 2 tabs where you can see it's an issue). I know the Edge team cares about attention to detail for things like this so I thought it was worth posting
