Reporting for VirtualBox as it is all I have used, unknown if hard installs work the same.
Launching most windows, but using the Software Center as an example the window is maximized when launched. Clicking the top bar button to window the application works, however, after that the maximize button no longer functions at all.
Although some applications like Firefox work well, the OS Installer and Software Installer and quite a few more definitely do it.
Installed & LiveCD
Virtualbox: 6.1.18 r142142 (Guest Additions not installed and after installed)