I had a customer send an a email Letting up know about the parts that he bought.
he wanted to share this information with us.
The Attiny414’s that I purchased from Digikey have the markings
Atmel 728B TK
These units do not have temperature sensor calibration data loaded onto them and therefore the internal temperature sensor is not useful.
I was told by Microchip support that the 728 marking means they are engineering samples and do not have calibration data loaded.