There are two factors at work here, and fortunately both are normal and not of concern. This looks like a Southern Magnolia (Magnolia grandiflora; not all individuals have the classic deep brown fuzzy leaf undersides). It's normal for these evergreen trees to shed their older leaves in autumn, which explains the yellowing of some foliage in the inner and lower regions of the canopy. Actually, Southern Magnolia tends to shed a small portion of its older foliage year-round, but autumn's shedding is perhaps a bit more prominent, especially as they mature.

The blotchy yellowing on certain individual leaves is due to a leafminer. Leaf-mining insects belong to several taxonomic orders (flies, sawflies, moths, beetles), and they feed as larvae between the upper and lower layers of a leaf. The browning seen here appears to merely be tissue that has desiccated and died after being fed upon. Leafminer insects don't cause serious damage to their host plants, and the plant will shed its damaged foliage sooner or later as replacement growth is produced. The undamaged portions of leaf can still photosynthesize normally and still serve to feed the tree. This one is probably the aptly-named Magnolia Serpentine Leafminer Moth, a native insect. Here's a sample gallery, including mines primarily formed on Sweetbay, our most widespread locally-native Magnolia species: https://www.marylandbiodiversity.com/view/5576

If bothersome, you can pluck off the handful of mined leaves and dispose of them. The plain yellow senescing (shedding) leaves can be left to fall on their own, since plants recycle via reabsorption some of their leaf nutrients before the leaf falls.

Miri