LC Casserole damage

Hello

I own a Le Creuset Cast Iron Round Casserole. Despite it looking extremely sturdy, it has developed a spot of rust or rather almost a whole with a rust surface right next to the handle. This is totally random but I noticed on an influencers video who owns the same casserole that she has the same damage. What is it? How did it happen? How can we prevent more such damage? Thanks in advance!