How to capture `super` key pressed event in a gtk application on ubuntu?

We are developing an application that requires the program to capture the super key event on Ubuntu. However, there doesn’t seem to be a way to do it. Whenever the super key is pressed, it opens up the activity center on ubuntu and zooms out of the current application. If I run the “xev” in the terminal, the super key is also not captured. Only the zoom-in and zoom-out are recorded. Since I am no expert on keyboard problems on ubuntu, we really need some extra help from the gnome community.

Some extra info:

libgtk-3.0:amd64 version: 3.24.20-0ubuntu1.1
OS version: Ubuntu 20.04

Run xmodmap -pm in the terminal returns:

xmodmap: up to 4 keys per modifier, (keycodes in parentheses):

shift Shift_L (0x32), Shift_R (0x3e)
lock Caps_Lock (0x42)
control Control_L (0x25), Control_R (0x69)
mod1 Alt_L (0x40), Alt_R (0x6c), Meta_L (0xcd)
mod2 Num_Lock (0x4d)
mod4 Super_L (0x85), Super_R (0x86), Super_L (0xce), Hyper_L (0xcf)
mod5 ISO_Level3_Shift (0x5c), Mode_switch (0xcb)

And my /etc/default/keyboard is