As a contractor I sometimes visit a federal government building in northern Virgina. I've noticed during my visits that inside the building at individual cubicles there are small pride flags, and on the wall are building-sponsered signs that advertise "gay ally club" events.

Is this legal using taxpayer dollars? If not, how can I bring this to the right people's attention?

To me the pride flag is a political symbol, so would fall under displaying a Trump 2020 or Biden 2020 flag.