I recently made this edit. Strangely though, it includes changes that I did not make.
I did make all of the changes outside of the code block, but I did not delete the comments within the code block. My intention with this edit was to do some basic grammar/spelling/formatting changes, and deleting those comments totally changes the meaning of the post. I'm glad that it got rejected because I would have rolled it back, as it is a very bad edit in its current state.
I'm not sure if this will be reproducible or not- I've never encountered it in the past, but based on the post above it seems that something similar may have happened to other users in the past.
I found this question answered by Jeff Atwood that seems to be the exact same situation (I didn't see this in my initial search).
I think that some warning to the editor would definitely be nice in this situation. Also, in my situation, this effectively caused changes made by the author during the grace period to be rejected, which (correct me if I'm wrong) is not currently possible otherwise.