What orientation are these in terms of compass direction? I already know the answer, but it's interesting to consider. In our part of the world, the primary sun exposer is from the south - meaning southern facing solar panels will absorb the most energy so to speak. So do you suppose the leaf change is happening more on the southern or northern side? Or, is it all genetic, and sun exposer doesn't matter?

Looks like powdery mildew

It's a type of fungal infection. Typically powdery mildew doesn't cause much, if any, harm to the plant. Fungal infections in trees come in a variety of different types, many of which are quite harmful (Needlecast in Spruce for example) Dense foliage often causes lack of sunlight penetration to the crown interior as well as reduced airflow. These two coupled together lead to a moist environment which is prime breeding ground for fungal infections to form. Disease prevention is a good reason to have trees thinned periodically

Experience obviously helps a lot. But I think it depends on how you are loading the branch attachment point. Rigging or climbing on an included area will vary greatly from wind or snow load. Guess we'd need to understand the application you are suggesting in terms of force being applied.

@Timo C Excellent! Where are you located in the world?

@Isaac Briggs What is your best guess at species?

@Timo C you are correct that it's an Oak! And these spots do often show as a result of deadwood, however in this case I was unable to observe any additional signs or symptoms. The tree as a whole is in very good condition. Seems strange to me how square the markings are, as if man made somehow.