I mean, they actually might be via their vote history. But in some of these states, particularly in PA but also MI/WI as well, you're going to get people who are registered (PA) or model (MI/WI) as Rs who will end up voting for Kamala Harris, and that number could be not-insignificant.
Like, if Harris ends up improving her margin in Waukesha County, she isn't necessarily doing it by turning out more people who model as Ds.... she's persuading people who model as Rs.