That's because Republicans realized their voters vote based on culture and identity stuff vs. policies. In one way its why Republicans are good at the art of politics and Democrats suck at it. This entire fight over the Democrat's agenda sorta paints this picture. Democrats think if they provide all these popular programs people are going to be thankful and vote for them. People may enjoy the programs like social security and medicare which Republicans would love to destroy policy wise, but they continue to vote for Republicans because of culture and team sport politics.
Yes, a lot of it is white identity racial issues, but every single election in probably the last 30 years the republicans gin up some cultural wedge issue because they realize it's the only thing their voters actually care about. The other reason is, for the most part, people are too stupid to understand complex policy ideas or the nuance of solutions; Republicans are great at messaging and boiling things into simple talking points whether they are true or not.