Yes, you can resize the initial window. If you do, then double clicking afterwards will alternate between maximized window and the resized window. So once you resize the original window you should not be able to trigger this issue.
I don’t have access to 0.8.15, but I see in the release notes
“MacOS can now double click the frameless window header to zoom or un-zoom.”
Which I assume means that this issue is no longer “solved” by the frameless window.
Presumably the fix would be to assign a (reasonable) size to the initial window on first launch. Then double clicking the title bar should maximize and un-maximize the window.
Launching with a window that fills the full screen on first launch doesn’t make too much sense anyway, because the user (most likely) has no data at this point, so no need for a giant window.