When you do File->Open file... it should close the window that open when you press the ESCAPE key. It does when you do File->Open URL... but it does not when opening a file, or when in the configuration menu. This is how I interact with pretty much all applications in KDE. Minor inconvenience but when you're used to that behavior, it is like something is broken.
https://invent.kde.org/multimedia/haruna/-/merge_requests/91