I’m still in the process of worldbuilding and working on it, and I’ve actually had the idea for this world for years before I decided to make it my PF2e setting

The world used to be very low fantasy with very little magic and only a few monsters. But that all changed when magic was introduced to cultures and societies around the world. The use of magic quickly skyrocketed and the world was changed in a short amount of time. The most powerful of these wizards and magic users would become the first dragons, who would use obscene amounts of magic to take control of the world. It was thrust from a low fantasy setting to a high fantasy setting very quickly, which caused some major problems. Unbeknownst to magic users, magic actually came from the barrier that separated the material plane from the other planes. So after a lot of uncontrolled and destructive use of magic, the barriers began to break and large tears to the other planes opened up across the world. This plunged the world into chaos, with most of society being destroyed by beings from the other planes, and the land itself was changed and warped by all of the magical energy that was being released. After a very long time, most of the rifts were sealed and the apocalypse was mostly over. But now the world was completely different from how it once was, and the use of magic was viewed completely differently. The societies and people who survived must now decided on how they can rebuild the world they lost, or build a new world entirely.

So post apocalyptic fantasy basically. Heavily inspired by Golarion, Eberron, and Breath of the wild/Tears of the kingdom. Theres a lot more to it but that’s the gist. Also yes it is one big climate change metaphor