Yes, you shouldn’t change vertical margins in the editor. Changing margins in Reading view is fine.
via Licat (03/11/2022) in the Discord #theme-dev channel:
The editor measures and predicts where elements are located on the page so that when you scroll around, parts of the page that’s out of view can be removed to keep the editor performant. Using margins completely breaks the ability for the editor to do that because margins don’t behave predictably due to the margin collapse algorithm
and another post:
Margins breaks the editor, you need to use padding instead