I forget which report from which data analytics/polling group I was reading a few days ago, but their major takeaway was that split tickets are getting more and more rare in this partisan environment and that they were fairly rare to begin with, it was one of the key reasons they had serious doubts about public polling results.
There has been one split ticket in the last 2 elections. But recent polling kept trying to tell us to expect a bunch with Dems winning comfortably in some senate races but Kamala losing by a point or two.