Anyway I suspect the binaries don't contain any mqtt support hence the message show mqtt is an invalid command.
serial arduino monitor (ssid is masked as is the password but the full values are working)
The serial monitor is sending NL CR and wasn't changed between the show and show mqtt
CMD>show
STA: SSID:PHxxxx PW:xxxxxxxx
AP: SSID:MyAP PW:none [open] IP:192.168.4.1/24
Clock speed: 80
CMD>show mqtt
Invalid Command
CMD>