Whatever is responsible for reading °C in your GPU is faulty, 10°C is fake reading do don't be fooled by that, always make sure you crank up your fan speed to something like 65% just to be on safer side, I once have a weird GPU with same issue before
Very doubtful. The card has been running reliably for 4 years like this including 4 Australian summers where ambient exceeds 40 degrees C. Also both the GPU and hotspot reported temperatures are 10 degrees lower than usual. And if there was a measuring error then the backplate would be noticeably hotter but if anything it's cooler than the other cards.