When MQTT v5 integration was finalised, this was removed (for reasons I cannot answer).
however...
are you connected to a V5 type MQTT broker & are you using the V5 "Payload Format Indicator" in your applications?
Is this actually causing you an issue?
Are you validating the payload & issuing a PUBACK, PUBREC, or DISCONNECT with Reason Code of 0x99 (Payload format invalid) as described in section 4.13.