This is actually not the easiest thing to pin down, but the best analysis I've seen is at https://www.usgovernmentspending.com/year2022_0.html.
In summary:
17% to pension programs (e.g. social security)
23% to healthcare
19% to education
12% to defense
7% to welfare
3.6% to police/fire/prisons
4% to transportation infrastructure
14% to everything else (scientific research, the courts, the Department of Agriculture, etc.)
The US budget deficit doesn't come from overspending in any particular area, and there is no single fix that is going to get us back to parity. A focus on efficient spending and reducing waste might help, but it would need to be applied systematically across the entire government.
We are simply spending too much money everywhere, and getting too little value for the expenditure.