The thousands of degree temps are right, Vega pulls a lot of power so AMD designed the heatsink with a passive liquid sodium cooling system, same type of system which cools modern nuclear reactor designs.
Just kidding, yes it's a faulty reading, nothing to worry about. Could be the software reading error, could be a faulty sensor, or could just be faulty data transmission for that one second because a cosmic X-Ray triggered a million years ago from a star hit your computer.