The plane is our office. Our workspace. You chat at your workspace with your colleagues, we do the same at ours. A 5.5 hour red-eye transcon can be a long time to not chat with people. However, we do tend to not realize how loud we can be. I myself have several times been sitting on the rear jumpseat chatting with my coworker, only to non-rev in the rear of the plane a few days later and be appalled at how loud the FAs are- only to then suddenly wonder if I am that loud as well?

The solution is to tactfully, politely, and respectfully approach the flight attendants, acknowledge that you understand that it is their workspace and whatnot, but calmly and politely request that they take the volume down.

Hope this helps in the future.