Overall I can see what you are saying, but there are a couple issues I have with this check. The first source shows different VP debate results and the subsequent election, but there really isn't anything to definitively say that those debates were key factors. It may be true that this is misleading, but there isn't exactly evidence to go against it. Also, things like the lack of time between VP debate and election limiting how clear the impact is seem to be true, but it doesn't change the fact that with the modern election calendar, vp debates don't have a very clear impact. The second source that focuses on Vance and Walz's recent debate says they aren't usually important but that this one is with little evidence, making it seem a little reactionary. It is easy to imagine that being said for several past elections as well where there was little obvious impact, and the basis of this claim seemed to just be because the current VP candidates contrast heavily.