I worked at a gourmet dessertery some years ago. Owner wouldn’t let us leave a pot of coffee over 30 minutes on the eye. He was right. The flavor ‘burns’.
Iced Tea is the same way. McAlisters Deli won’t keep tea over an hour before they toss it.
It’s very good because it’s always fresh.
Commercial Bunn style coffee makers do tend to have hotter pads than most modern home drip makers. If I forget to turn mine off and have just a little bit of coffee left in the pot, it will dry up of course, but it will not burn it into a black carbon residue.