Drawings drawn with graphite shine a lot under even a little light. The paper needs to be held at certain angle for proper viewing. Anyway to reduce or stop this?
Spray fixative should make the drawing more matte as well as protecting it.
You could also try a layer of acrylic matte medium, sprayed or brushed, but that would be a little more involved and riskier to the original work if it cannot handle the wet medium.
Either way do some test pieces before trying on the finished work.
I also would recommend drawing with a softer lead for dark areas, it will require less working and less material to get the tone you want, which means less buildup and less gloss.
There is a type of spray that is often used by film production teams called “dulling spray”. It is a spray that kills reflections on anything, because in movies you DO NOT WANT HIGHLIGHTS.
The spray is expensive and quite a challenge to come by, as the best sprays are only distributed by photography and film equipment rental shops.
If you do use it, always spray very light coats - and definitely do a test on another piece of paper before you risk ruining your work.