Apple Watch Ultra Action button fell off due to rust

So before I go sleep I went to do some usual cleaning of my stuff before I put in charge. that's just easy cleaning with a microfiber cloth. I have my watch since it came out. first thing got my attention how dirty it was but for some reason it didn't felt right cause haven't been doing anything. that caught my eye that action button was a little off. and it fell right off and there are tons of rust everywhere inside out ! but it still works like a charm. Here are some pictures : most weird thing ever happened