Budget

The last time the congress reformed the budget process was 1974. The congress can investigate and issue subpoenas but the president can refuse to enforce the subpoena. Thus the only power the congress has to investigate is when the congress and the president are the same party. If the republicans take the house they will investigate a number of situations but it will all be for show since Biden does not have to enforce their subpoenas. The real power of the congress is the purse but since the government no longer passes a full budget this is difficult. Instead of a passing a full budget each year where each item is considered individually the congress instead passes what are called omnibus bills and they are usually some huge number and contain all sorts of various programs including a lot pet projects. If the congress wanted to hold hearings with teeth they would withhold money until subpoenas were enforced and to do that they would have to stop the whole budget to get at one part and that would shut down the government and they don't want that. The past two years the democrats have had the congress and the White House so they can investigate and enforce subpoenas and that is just what they did.