I think it’s more specific than that. The 2008 surge of young people to democrats was driven by rage at the failures of two institutions: the banks (the Great Recession), and the intelligence apparatus (Iraq war). But those institutions never were reformed, and today the Democratic Party has become the staunchest defenders of the banks and the intelligence apparatus.
But for Gen Z folks, that stuff is ancient history, isn't it? Even the oldest members (using 1997 as a starting point, but some definitions use 2000) were too young to protest or serve in Iraq[1]. By the time the youngest Gen Z folks were starting school in the mid-2010s, the US stock market and unemployment rate had reached pre-recession levels too.
[1] I mean when people cared about Iraq, 2003 to circa 2008. We still have troops there, but I don't think most of America is even aware of that.
Both of those institutions were, in fact, heavily reformed.
What you actually mean is that there was little personal legal accountability for past actions, which I don't disagree with. The legal and political frameworks they operate under has changed quite a bit though.