It would be better if someone could provide a closer, hands on look a the situation and you might want to contact your local extension office to see if they have someone who can do this.  That said, if you are taking down trees in the area, the extra light may result in some burning if the trees that are having problems have gone from a shade environment to a direct sun environment.  Usually that would be seen on the new growth, not deeper in the tree.
Over time, you might get what you see as a natural response to growth blocking out the light to inner parts of the tree and the tree responds by dropping some leaves since they no longer get sufficient sunlight.
You mentioned spider mites.  You should be able to see the actual mites or the webbing they produce as they move between limbs.  Take a closer look at the affected areas.   If you have a hand lens, use it for a close look.  If you have mites, you will see them.
Another possibility is caused by one of several species of fungi and the disease is called needle cast disease which is due to excessive moisture from too much rain, a naturally wet environment or drought which stresses the trees.  Different fungi may infect the tree under different stress conditions.
The following web page from Minnesota Extension will give you more details on this disease.
https://extension.umn.edu/natural-resources-news/browning-needles-spruce-trees