This is overstating it. Among white voters, college graduates preferred not just Republicans, but Trump, by a 4% margin (and by 14% in 2012) [1]. The sorting along racial lines seems the more obvious one.
Given things such as the (attempted) explicitly racially discriminatory prioritizing of funding by the Biden administration [2], can we really be surprised?
[1] https://www.pewresearch.org/fact-tank/2016/11/09/behind-trum...
[2] https://www.nytimes.com/2021/06/23/us/politics/biden-debt-re...