the leaves look like a bug is eating leaves (chewing edge of leaves and into leaf) also very few flower bubs. Shrub is about 5 years old. Also some brown and black spots.
You say this is a magnolia shrub – usually magnolia are classified as trees and yours seems unusually small for a 5-yr old plant. Are you sure it is a magnolia?
In terms of general care, magnolias like full sun and free-draining acidic soil that doesn’t dry out. They are surface rooted, so cultivate the soil carefully, if at all, under the tree. They don’t like grass growing right up to their trunks and they like lots of organic material in the soil and mulch on top of the soil to retain moisture.
Magnolias rarely suffer serious damage from diseases and insects. Very young plants can be attacked by slugs, but they are easy to control with modern baits. Sometimes, the leaves are attacked by leaf miners that chew through both leaves and flowers. As these insects rarely kill the host plant, you may choose to live with the problem, if in fact, leaf miners are the problem. It is hard to know without a bit more information (damage to leaves other than holes? any larvae seen?) or perhaps a picture of the leaf damage.
OMAFRA – Ontario Ministry of Agriculture, Food and Rural Affairs – has an excellent Fact Sheet on Leaf Miners attacking Greenhouse Crops. This isn’t your situation, but this article has excellent pictures of leaf miners and the damage they cause and strategies to use to control them.
This is the link: https://www.omafra.gov.on.ca/english/crops/facts/14-037.htm