@gazumped on windows, the fullscreen mode is - in my opinion - for more cumbersome than the keyboard oriented aero-snap feature. Also, a fullscreen application in windows cannot share the display as a macos fullscreen application can. So I would argue the windows aero-snap-feature and the macos fullscreen-split-feature are more use-case congruent.
The issue arises in them handling the windowing differently. The macos split puts both windows necessarily into fullscreen-mode, thus raising the issue of that mode being escaped when pressing, well, 'escape'. The most annoying bit is to constantly having to rearrange your split-view-spaces because you pressed escape, trying to get into the note-list or navigating in the editor (this comes mostly from muscle-memory developed by working with vi). Noteworthily, other text-editors, and indeed many other applications in general, have recognized this as an issue long ago, so evernote is the only application I use (very) frequently that still struggles with split-view-friendliness.
Having thought about it a bit more (and tested other applications for it): other applications merely ignore the 'escape' when in split-view-mode! So I should specify this in the title, presumably.
The only moderation-action I can take is deletion. If you deem the moving of this discussion as fruitful, I kindly ask you to!
(or maybe I just delete it and restart at the correct place?)
Edit 2: the more I think about it, the more I feel that this should be placed as a bug, since the surfacing expectation of meta-usage of similar applications and their patterns suggests uncommon or even perceived faulty behaviour in specifically split-fullscreen-mode. Escaping, let's say, a search from the find-in-note-search with 'escape' and escaping from editing to the next "higher" interactive element are not far from another; yet one triggers leaving split-view, the other doesn't.