Biden's poll numbers started tanking when he/Mayorkas started lifting the restrictions at the border, which then acted as a magnet for more people to come. Mass immigration is not popular with any voting bloc, even Latinos, who then have to compete with the new arrivals for housing and jobs. In fact Trump did better with Latinos and Black male voters than Republicans typically do, possibly due to his hard stance on the border.

Voting Rights and Policing Reform. Many PoC and others are very disappointed that Dems/Biden are not going to the mat for voting rights while the GOP runs their suppression game all over the country.

Supply chain/inflation/gas prices. It's the economy stupid as Big Dog told us. Voters will always blame who is in power and there is no way to get around this. Biden has to do more to solve these issues or Dems will pay.

Afghanistan. Alot of women voters and others felt the withdrawal was grossly mismanaged, and now the Taliban is control of the country.

Covid. People are just sick of covid and will blame whoever is in power if it is not solved. Biden is doing all he can, but the dummies won't take the vaccine. Hopefully the antiviral pills will be a gamechanger that will sharply lower hospitilization and deaths.

Crime. crime is up greatly in many major cities which are mostly controlled by Dems. Adams was elected in NYC in response, we'll see if he creates a new template that can balance racial/social justice with safety. Being a black man and former policeman he would have the best perspective.