Dear ChiTuBox, After v3.4.1 firmware, photon-s support A/A. But this firmware not compatibile with chitubox. Recently released v5.0.0 compatibile with chitubox. Thus you can support A/A option now!
Far as i know it's down to anycublic, the new file format is locked down and it's the only only that lets the printer use AA, the old .photon format can be used still to print but without AA so i guess it needs anycublic to unlock the new format they use so 3rd party software can use it.