Probably what the money was spent on should be taken into account too.
Most campaigns stretch the truth a bit here and there, but from what I personally saw and from what I read from other states where the campaigning was more intense generally the Harris campaign did not stretch nearly as far as the Trump campaign.
I'd expect that this let the Tump campaign get more out of a given amount of spending than the Harris campaign could.
[0] https://www.usnews.com/opinion/articles/2024-11-15/trump-har...