I added a W-2 for United Public Health Serv and marked it Active military duty. However, TurboTax keeps asking for my military W-2. Why is this happening?

PHS is a uniform service as is the military but it not  combat service.

Does that mean it doesn't count as active military duty for tax purposes?

The U.S. Public Health Service is a "uniformed service", but it is not part of the United States Armed Forces (the "military"). The Armed Forces consist of the Army, Navy, Air Force, Marine Corps, Coast Guard, and Space Force.

https://www.law.cornell.edu/uscode/text/10/101#a_5

https://www.irs.gov/individuals/military/eligibility-for-military-tax-benefits#:~:text=Uniformed%20Services%20of%20the%20United,Atmospheric%20Administration%20Commissioned%20Officer%20Corps