KC868-M16v2 configure yaml for ESPhome

[admin]

because you have only connect L and N with L3 and N3. your yaml file is print voltage channel one.
it.printf(0, 40, id(roboto), "AC:%.1fV", id(voltage_1).state);
you can change to :
it.printf(0, 40, id(roboto), "AC:%.1fV", id(voltage_3).state);

or you can connect L1,L2,L3 together and N1,N2,N3 together.