Don't know how else to tell you this, but literally every portion of the message from Hegseth to the group about aircraft takeoff times, airframes, ToTs, was SECRET at a minimum. Anything that describes the movements of men, weapons and equipment is SECRET. Then, compilation raises that to TS.
Every single member of the DOD who has access to S// or TS// systems takes a Cyber Awareness and Derivative Classification course every year. It's pretty basic stuff.