The Unity Editor has 2 menu items, Save Scene and Save Project. The distinction is vague and cause people to lose work. I can’t find any information about saving in the Manual.
For example: Unity just crashed to desktop and lost 6 hours work! - Unity Engine - Unity Discussions
And there are a ton of similar threads: https://www.google.com/search?q=“save+project”+site:forum.unity3d.com
My suggestion is to add a page in the category Unity Basics about saving in the editor, explaining the rationale and difference between the 2 menu items, that dirty assets are not written to disk until exiting the editor or using the Save Project menu item, and maybe throw in some references to asset serialization and versioning as well.