Funding for specific projects that are added by members of Congress to appropriation bills, usually without oversight or public debate, is known as

The answer is - Earmarks.

Explanation:

Earmarks are hidden funds that are provided by Congress and put in discretionary spending appropriation bill for specific projects and programs or to exempt specific people from paying federal fees or taxes. The funding are usually without oversight or public debate. The funds from the earmarking can be used for parks, laboratories, research project e. t. c.