Service members are anyone serving in the military.
Warfighter is used to describe combat roles.
If useful to distinguish between the two, warfighter is the correct term.
The POGiest of POGs are "warfighters" and individual organizations within the DoD proudly advertise how they serve runny eggs and chicken to warfighters every day or issue their uniforms/equipment with incredible lethargy or maintain their personnel records in 20+ different systems duct taped together.
"Service member" does get used a lot still. Usually abbreviated to "SM".
Source: Personal experience in both combat arms and non combat arms roles.
He (and his allies) have referred to him as "warfighter": https://www.radiofree.org/2025/04/23/look-ma-im-a-warfighter...
It would be like a barista becoming CEO of Starbucks and saying, "the employees are happy to have a barista as CEO."