This take doesn't represent the full picture. First off, a lot of liberals vote more red now than blue because while they see flaws in our history, they don't see them as a reason to "end the American experiment" and tear everything down to build a new world order, as leftists often say. No conservative I know thinks slavery should be brushed by, or racism, sexism, etc. We're just often responding to leftists demanding that because our history contains those things, we should abolish America as a whole, or start prioritizing other countries rather than our own because our country is trash because of our past. Also, conservatives don't buy into the 1619 Project bull, which claims that America was actually founded in 1619 instead of 1776, as a ploy to make America's foundation solely on racism instead of freedom.
A liberal may be more critical of our past than a conservative will be, but I have no doubt that neither wants to see America ended for it. Leftists come in and point out those flaws and try to destroy the country because of it. And at the end of the day, it's just a cop-out. That's not why leftists really want to destroy America. They want us out of the picture because we're the last threat standing between them and world domination. Sometime in the last several years, a lot of conservatives woke up to the fact that this was going on, and the leftists started pretending we were viewing our past with rose-colored glasses and hiding behind liberal ideals that are nowhere near as radical as their own (like they always do).
Kamala Harris was a very far-left politician who, like whoever was running the country for the last 4 years, would have made many classical liberals feel once-again alienated. Her VP choice, Tim Walz, his wife literally said she parked in Minneapolis and soaked in the smell of burning tires during the George Floyd BLM riots because it was a sign of "change", before Tim Walz took 3 days to call in the National Guard (while his daughter warned the rioters when they were coming). Tim Walz and his family literally were involved in the destruction of Minneapolis. While many conservatives sympathize with George Floyd (and tbh that whole situation was a hoax but I won't get into that unless you want me to), none of us feel a whole city should have been desolated for it. That is the difference between the left and the right now. Red and Blue is not Conservative vs Liberal anymore, but Conservative/Liberal vs Leftist.