Oh, that's easy.
1) lack of transparency regarding Epstein files
2) Complete mishandling and deployment of ICE officers going after non violent illegal immigrants/undocumented workers. (complete misuse of resources imo and squandering support from the Hispanic voting base
3) pardoning of Binance CEO
Changpeng "CZ" Zhao. and then continuing a financial/business relationship with him. (clear conflict of interest here)
4) Petty name calling of journalists who ask perfectly legitimate questions
5) failing to deliver on peace in Russia/Ukraine. (this was/is a continued difficult endeavor and him saying he'll end it in the first day in office was ridiculous
6) using hyperbolic comments like, "this is the best economy we have ever had...we have lowest grocery prices ever..."
7) as much I despise the democrat party, He has inflamed the partisan divide. This country is the most divided I have ever seen.
8) How he handled the election/January 6th
there are many more, but this is just off the top of my head.