It’s the UI setup. All DE/WM combinations are, and have been, factually inferior to Windows Explorer in terms of optimization, clarity and animation.
Which may or may not be because of their excessively modular structure and fractured development. Each layer has its own opinionated dev team unlike in Microsoft or Apple, where it’s all synchronised and everyone across the board have (at least at the time of development) a clear vision of the product they want to make.