This does not happen every time that I use Alt+Tab to switch to a different window but often. The other instances of Opera GX are not actually open in different windows but they clutter my screen a lot whenever I use Alt+Tab again and I am not sure what to do about it. I have gotten the window manager to crash by repeatedly switching tabs before which has effectively rebooted it and fixed the issue that does not fix the actual problem. Not sure if others are experiencing the same issue so I provided a screenshot of how it looks for me when I Alt+Tab.