Another FYI. One of our admin thought they were doing the right thing by setting our "root block element" to div instead of p tags. They did it because they didn't like the email editor adding p tags which can cause spacing issues in some clients. However, using <div> tags as the root block element causes the aforementioned spacing issues. I switched it back to <p> tags and the spacing issues stopped. You can switch it here: Admin > Email > Edit Text Editor Settings > Email / Snippet Editor
Now that it's set back to p tags, if I add spaces in the editor (which I rarely do) I just change it from "double spacing" to "single spacing" to avoid p tags being inserted and potential spacing issues.
Adding a double space seems to default to a single space which has worked for me.
The code still sits on separate lines but removes any unwanted spacing.