We do know what's causing the flare, it's the lens. This has always been the case. The green color is caused by the anti reflective coatings on the lens. The sensor has little to do with it but in rare cases even the sensor can reflect light back into the lens elements, but when that happens it is typically red in color and there are many of them. Adding a polarizer or any other filter will always make things worse because you are introducing another air/glass gap into the lens grouping, which is how flare comes to be in the first place.
Everything has been explained earlier in this thread, and even $15,000 DSLR lenses are not immune to flare if you're going to shoot directly into the sun like many people seem to like to do with their drones. If those lenses can't completely defeat flare, a simple polarizer or the
M3's cheap lens group isn't going to stop it either. It's a fact of life with photography and you just deal with it.
Which pros are telling you a polarizer helps reduce flare? I've been a professional photographer for over 20 years and that is certainly not my experience nor have I ever seen evidence of it. It doesn't make any sense.