Let World2D handle mouse inputs, without push the input.

[balmy reef]

but debugger don't stop by the breakpoint of the first line of code from _on_input_event().
The debugger doesn't randomly decide to skip breakpoints. This means that the program doesn't hit that first line of code.

So your code (and flow) isn't doing what you think it's doing. Use more breakpoints and stack traces to figure out at each step what exactly happens and why.

You might also want to read about MouseFilter and check your own nodes to see if it's set up correctly.

[balmy reef]

My code works fine,
Highly doubtful, otherwise we wouldn't be here. When you run into any issue, you should be running on the assumption that your code is wrong.

You do this: subviewport.handle_input_locally = true, yet want to handle input outside of that subviewport? Did you write/understand your own code? 😒