5V ultrasonic device on Arduino, might've broken non-5V tolerant wireless module

arusr:

fungus:
Where does it say that on the datasheet?

Assumption on my part. It doesn't make sense to that the reliability is the same across the entire operating range of operating temperature for the same voltage/frequency combination.

Yes, but you're just guessing at the answer and going against the advice of the people who actually designed the chip(!)

Is it good practice to guess at whether it will work or not when you're selling product to people for money?