Hmpf... I will ask at Dell then about this, but I doubt they are interested in changing this back. I also noticed the SMART information says "Drive Temperature" and "Drive Temperature 2", is this also due to the Bios/EC, or is this always named like that or by the specific drive?
I too doubt they will change that or provide some clarification. The interface used to provide these values is very secret.
Drive Temperature is independent from that. If it's a NVMe drive, the first value is most probably the media a second the controller temperature.
I don't know why they did it. It's quite possible there's some new function to retrieve this information.
I have requested information about these functions some time ago and even though I have an NDA with them and good contacts, my request was denied.