I do not believe those are all airbrushed out. There is one that is faded right next to a very clear one. It looks like some of them have had the dust and dirt blow up into them. In fact, it would not surprise me if these giant hangar like entrances are not covered and revealed from time to time because of the shifting dust and particles.

If one were to explore those, I would believe that it would reveal long ruined structures, perhaps with desiccated or fossilized organic life at best. I think that planet was destroyed eons ago when the planet in the next outer orbit exploded for some reason. Perhaps the survivors of that cataclysm constructed a way to subsist for a time.

Good finds. I think we will learn more about Mars over the next 20-30 years. Hopefully we can keep our own civilization together so we can attempt to find the truth. Thanks!