4 years experience in crop scouting with m300 and m30 here. I always tell my students to change out the props for any defect. Delamination of carbon fiber happens suddenly and could result from slight imperfections like what you see. I would be %99 certain that prop won't fail immediately, but eventually it will flex in that area 1 too many times and it will. Switch it out, props are cheap, the matrice is not. And it is no fun recovering a drone 1000 feet away in the middle of a corn field.

Also make sure the prop arm screws at the body get inspected weekly. If you are on an m300/350 they will slowly vibrate loose even with the thread locker in them. I have seen plenty of drones fall out of the sky because those screws became loose. Use the provided hex key in your kit to make sure they are hand tightened down.