You are correct.
I was told and read yesterday that the Arab councils brokered the deal for those leaving. No foreign fighters included.
Object was to reduce the civilian deaths.
US military and the SDF wanted no part of it. Many units fighting in Raqqa were local Arab militia’s. That was done largely to appease Erdogan the Islamist.
My issue, after they leave with the civilian human shields what happens?
It is still unclear.
Simple, they are hunted down outside the influence of any local councils. Swift sure and complete.