Found: Fiction/medieval fantasy kinda?

Trying to figure out a book I read a while back; there are these 3 platforms, each circular and each rising higher than the previous as you move farther inward. Also I feel like I remember that this world is a floating island in the middle of the sky or something? Anyways, this guy (main character) who lives in one of the lower levels decides he's going to climb the cliff face up to one of the higher tier platforms (the more central and higher up one was, the higher their social class). Long story short he climbs up to the higher level and lo and behold, the higher tier platforms are actually sinking into the rest of the world. There's a castle and a battle at the end that was really dope, and eventually the highest level reaches level with the lowest (that's when war happens) and continues lowering even lower than the originally lowest level. There's something that's really important tho in like the basement of the castle and so it's problematic that it sinks lower than the low level because a whole bunch of water starts flooding up. There's a lot that goes on, great book. There's a second one as well where the guy from before (main character again) takes some space ship thing (ik it sounds very out of place, book sets the scene and makes it work) down elsewhere (turns out to be "earth" (i dont think this is explicitly stated but it's earth) where he finds these orphans essentially dying slowly bc earth is polluted af now, and this is why the sky place with the platform caste system was created. Anywho, no clue the name or author, google is no help. Sending out my SOS.

could maybe be from Margaret Weis' Death Gate Cycle? The first book is Dragon Wing.

Possibly Atherton: The House of Power, but it's been a long time since I've read it.

>3 curioussquared: this the one, thank you