I did some testing and the issue happens on any kind of page, with any kind of content (or even without content), and with or without the site header and footer.
However, the issue doesn't happen on experience fragments, template editing, layout editing, or other places... Only on author view, while editing a page.
There is a problem reported by some users, about that issue since AEM 6.1. I'm already running the latest version and the issue persists, on two different projects
Apparently, that issue is caused when there is anything on the page (component, header, or whatever) that has specific definitions on CSS. The definitions can be:
- position: absolute
- negative margin
- height with 'vh'
Tried the solutions suggested by other users in other places, none worked.
Couldn't find any official post from Adobe about the issue, and no official solution.