Many possibilities. In matrix metering, whites often get blown out. When we shoot white birds in sunlight, we usually set exposure comp from minus 1.3 to minus 2. I shot with the d850 for years- my favorite camera I ever held. But the metering did take some getting used to.
This does look like a clear day?? The sunny 16 rule should be close. If that assumption is correct, your exposure values are way off. Using your first set of values you are about 9 stops overexposed. Using the second set of values you are about 3.5 stops over. Although equipment failures can occur- in my experience the vast majority of the times (especially with a new camera), it is part of the learning curve. Learn to look at your images and adjust in the field. Turn on blinkies, learn how to read a histogram.
Personally I usually just shoot in completely manual mode, using experience to get close and then blinkies to nail exposure. But, if you want to stay in automated modes like program mode, the exposure compensation dial will be your new best friend. You probably need to adjust that for every new lighting situation.
And get out of program mode, P does not stand for professional. Try A, it gives you more control.
Go shoot some more.
Gary