I don’t believe it helps at need blind schools. They all note it. See Penn below when noting we don’t take your financial situation into account when making a decision.
I’m speaking anecdotally now but I wonder if a higher proportion of full pay to need aid apply ED. I would think so as full pay is more risk averse (binding commitment) and wealthier kids are more likely to know about ED, have counselors driving them to it and have access to test and essay help. ED would help and if more are full pay (pure guess) - that’s where that bias would come in.
Looking at CDS only 41% of last year Harvard freshman got need aid. Dartmouth was 46%. Perhaps there’s a natural bias of the wealthy to apply and while full-pay doesn’t help by definition, it helps in access to opportunities that make an Ivy education more a reality.
Pure guess on my part but ……
https://admissions.upenn.edu/admissions-and-financial-aid/cost-and-financial-aid