This is GNOME, not ratposion WM (https://www.nongnu.org/ratpoison/).
There should be a way to minimize using the mouse.
No. By default there are no maximize and minimize buttons. They were explicitly removed:
https://digitizor.com/gnome-3-maximize-minimize-buttons/
You can add them back with gsettings changes or "tweaks":
https://trendoceans.com/how-to-get-minimize-and-maximize-but...
This is GNOME, not ratposion WM (https://www.nongnu.org/ratpoison/).
There should be a way to minimize using the mouse.