Cross-platform GUIs shouldn't exist. That's it. They always inevitably are worse then native ones.
Just wanted to state that in other worlds, like C++, there exist tools like wxWidgets which provide cross platform GUI.
There are examples of the opposite, of course. IntelliJ IDEs, despite using modified Swing GUI, feel native-ish to me because Jetbrains put in enough effort to replicate macOS native behaviors.