The thing about these shifts which is always so odd is that posters on this site seem to view "trends" as something equivalent to the movement of continental plates--slow but inevitable. Parties are very capable of winning back over voters or changing people's minds with good messaging or with smart campaigns. Latinos in South Florida are a great example--for nearly 8 years on this site, there was endless discussion of how the traditionally Republican Cubans were shifting D, reaching its apogee with Clinton's strong 2016 performance...and then they flipped back hard in 2018 and again in 2020. Now of course the narrative is flipped the other way. In both cases the actual problem is a narrative which ignores the fact that people can be swung.
The same goes for Wisconsin. Barack Obama won 6 out of 8 congressional districts in 2008, significantly outperforming Kerry in much of the rural parts of the state. That's collapsed the other way in Trump times of course, but what that suggests is not the inexorable move of trends but rather switches in voter preference which are specific to candidates and their campaigns and positioning.
Of course, the problem is is that it seems like a lot of the political class thinks the same way as this forum which can make this sort of thing into a self-fulfilling prophecy.
I dont think 2018s performance was that unusual. It still reflected D swings from 2014 atleast.
Maybe a swing but certainly not a trend considering that it was a pretty good Dem year!