One can make a surface more diffuse without reducing the reflected power very much, or one can reduce the total reflectivity with a paint that absorbs some of the energy and reflects the rest. Taking "just a bit" at face value, there are clear matte lacquers that should increase diffuse reflection. Being a lacquer film on steel, removal if desired should be easily performed with lacquer reducer or with paint stripper.

I am not recommending this for any part of the hood that might be impacted by a flambé, deliberate or not. Also the hood should be high enough to not get warmer than nearby cabinets. Spraying lacquer of any type requires suitable respiration and room ventilation, with masking of anything one doesn't want lacquer on. In other words, pull the hood and do the deed outside or in an empty garage.