The “power to kwh” process doesn’t change the power value that it passes on to the next process. To do what you want you could use “reset to zero” followed by a “+feed” and select your kWh feed from the earlier “power to kWh” and publish that to mqtt eg

1 log to feed power1
2 power to kwh energy1
3 reset to zero
4 +feed energy1
5 publish to MQTT