EE=1, EO=1 Packet payload dropped from 84 to 66 bytes?

I am using XCTU 6.3.0 and I have two S2’s HV 194B running 22a7 firmware and both in API mode. The serial port is set to 9600/8/n/1/n where one is the coordinator and one is a router.

Per this article I should take 84-9=75 bytes for payload

Is this a bug in the documentation, firmware, hardware or XCTU software?

The size limit is dependent upon the type of encryption used and the twyp of network used. So yes, it can be either 75 or 64.