This exists in the current production version of Scrivener as well. Just verified it also is present in Version: 2.9.9.3 Beta (894377) 64-bit - 13 Apr 2020
The Windows OS setting for Mouse Wheel scrolling: “How many lines to scroll each time” should control how many visual lines of text are scrolled with each increment of mouse wheel turn. In my case this is set to 2 right now – a relatively low setting in most applications (even in the standard Scrivener editor)… But in the outline view, this setting causes Scrivener Outline view to scroll 2 outline entries (rows) at a time – even if each outline entry is taking up multiple lines, or in my case, 25-50% of the screen’s height or more. I would imagine that many people who use Outline mode may want multi-line entries, but this renders the Outline mode basically unusable since every time I scroll with my mouse wheel, whatever text I’m working on flies out of view. The setting of lines to scroll should correspond with actual lines of text, not with entries / rows in the outline, so for that reason I consider this a bug.