Switch turned off after restart

Every time I restart the Home Assistant server, one of my switches (a Qubino Flush 2) is turned off. The log only says “[Entity name] turned off”. The switch is used for lights, and the lights are actually turned off.

The only config option I find relevant in the Z-wave config panel is the state saving option after power failure, which is already set to on (state is being saved).

What could cause this behaviour?

Just a hunch…but maybe
MQTT Retain flag ??

I don’t use MQTT.

Did you use “initial_state: off” somewhere on your switch configuration?

Where can I find this configuration option?