No a huge deal, but I had some cliffs on top of some resources. When I went back later, having mined around the area and looking to see how much of the mine was used up, I noticed that some of the cliffs were gone and a deep core ore near where they used to be. I was now able to access and mine more regular ore uncovered by the cliffs. I don't think this was intended.

Hello,

That's indeed an interesting side effect :D

It might not be so simple to prevent and I'd say it's a rare case, I guess people remove cliffs when they can on ore anyway.