Tech support responded to my email thusly:
Thanks for reaching out but I am not sure I see the error you are mentioning. The description explicitly states this board has a 3.3V-tolerant SPI interface and a 5V-tolerant I2C interface. Both of those are correct as the breakout has pull-up resistors to 3.3V/Vcc so it can work with higher voltage systems so long as the input voltage is 3.3V. The Vin/Vcc inputs on this breakout are clearly labeled for 3.3V only and the Operation Voltage is listed at 3.3V as well. The user you are mentioning most likely connected the 3.3V pins to 5V, resulting in the damage to the sensor.
The tech support person obviously does not understand the meaning of the phrase "5V-tolerant interface", which means that 5V can be applied to the interface inputs without damage to the device. That is not the case
for the BME280 module in question.
Where does Sparkfun find these incompetent employees?
The fact is, many 5V microprocessor boards, including certain Arduinos, have pullups to 5V on the I2C lines. Those pullups cannot be disabled without hardware modifications. Connecting such microprocessor boards to 3.3V I2C devices can cause them to malfunction or even destroy them.