Ages ago, when I was a younger (around 2010-2015), I watched a 3D animated movie where the world was entirely sky (blue with clouds and stuff). It was populated with little planets of varying size where people lived and farmed, and seemed feudal/medieval. I remember the only way to get from A to B was bridges or some other way?
The main plot was something to do with the world falling apart (planets and their buildings disintegrating and floating destroyed through the sky). This blind king/lord met the characters to task them with stopping it at the beginning. By the end, when they had succeeded, he wasn't blind anymore and didn't remember who they were.
The movie has this scrawny leader character, a big strong one, and a weird dog thing (I think it breathed fire?). Somewhere along the way, a girl joined them as well. I remember the leader character berating the strong one at the beginning and saying the dog thing was cooler than him, if that helps.
I think towards the climax, they all had a falling out, and then the most memorable scene of the movie happened when this huge cathedral was falling apart, flying across the sky during a thunderstorm.
I do believe it was a kids' movie.
Edit: The language was English.