Maple tree issues
The red bumps are leaf galls caused by a very small mite - eriophyid mites. They typically only cause cosmetic damage, occasionally they can cause photosynthesis issues with individual leaves. I don't think that the galls are what's causing the issues with your tree. Is this the first year that you've noticed sparse growth in your tree? Has there been yard or construction work done around the tree in the last few years? Do you see anything else that seems out of the ordinary?
It was like this last year but not as bad. We haven’t done anything around the tree for several years. We put the flower garden around it. Maybe 7 or 8 years ago
There are many things that cause a maple tree to start declining - typically environmental stress that leads to the tree being more susceptible to insect damage or disease.. I'm going to put a link below that discusses possible causes and management strategies. I would also suggest that you have a tree service out to look at your tree. Many companies provide a free consultation.