I found a bug, that the Number Input Component is not reacting to the OnChange Method instandly, but reather only after you click outside the window.
For the Text Input Component (and many others) this also works if you make changes without clicking outside the window after you changed the value.
you can reproduce the issue, when you DO NOT USE the stepper button or arrow keys.
If you just change the value by entering the number via the keyboard, that the onChange Method does not work.