Send JSON to MQTT with Tasmota not working

[raduigret]

Discussed in #21477

^{Originally posted by raduigret May 23, 2024}
I have 2 Tasmotas flashed with same standard FW.
On tasmota A, if I send JSON format via UART, it is send via MQTT as below:
MQT: tele/tasmota_234e33h/RESULT = {"SerialReceived":{"test":2}}
but on tasmota B, if I send same payload, it reported as below in console:
CMD: {"test":2}

Both have same configuration:

the only exception is that A (that works) was configured some months before and I forgot what default settings I changed and runs Tasmota 13.4.0.4,
while B (that does not work) has Tasmota 14.0.0 and default settings.

Please help me how to configure it to send received json from serial via MQTT as above.

[sfromis]

Do not open an issue when there is already a discussion about how to make it work.