Thanks for pointing me to ShortcutDetective, gotta love those very specific utilities. You don’t often need it but when you do, it’s a lifesaver.
In my case, the keyboard shortcut is occupied by Logitech Options Daemon:
This is totally unexpected to me. Now I have to figure out why would the daemon need this shortcut and how can I take it away from the daemon and return it back to DT. Thanks again for the very helpful tip! 