Can confirm this bug is still happening, but it only appears to happen on my laptop and not my desktop computer. My laptop is a 4K display and my computer uses x4 1080p monitors. Perhaps that has something to do with it?
Quoted this reply to say it worked for me as well. Centering the first viewport on center fixes the issue of the window increasing it’s size by 2x8 everytime it closes.
Additional viewports are never affected by this bug.