I'm surprised at the giant blind spot so many analysts have about America's suburbs, which seems to be generated from a stagnated understanding of suburban demographics. Here, in this @538politics piece, is a great example of how this stagnated perception of suburban demographics
affects political analysis (profoundly). And I'm highlighting this piece by @baseballot but he is by no means the only 1 doing this- pretty much everyone is. Here is the claim and the otherwise fine analysis of primary turnout it appears in https://fivethirtyeight.com/features/historic-turnout-in-2020-not-so-far/
There is this prevailing (and flawed) assumption that suburban realignment, esp since 2017, is driven by former (white) Republicans "trying a new party on for size" and that w/o this, former R strongholds could not be flipping to Ds. 1st off, party reg data shows that much of the
exodus from the GOP occurs BEFORE '16 & analyses do not suggest much, if w modest declines after that cycle (based on states w party reg). Rs carried these districts in 2016 w the help of these Rs. They lost these districts in '18 though primarily through https://www.washingtonpost.com/politics/2020/02/28/first-time-ever-there-are-fewer-registered-republicans-than-independents/

diversification is also pushing them to the left, and non-white voters, just like other non-Trump voters, also massively increased their turnout. And again, this distinction is super important. https://www.citylab.com/life/2019/11/suburbs-demographic-trends-population-data-immigration/601546/
So yes, the suburbs flipped from Red to Blue in 2018 BUT its not primarily (& def not ONLY) because of GOP voters voting for Ds, its bc the demographics have changed & now Dem-friendly voters (Ds and Is, whites and non-whites) are showing up. https://newrepublic.com/article/156402/hate-ballot