MQTT Fan - What speed payload value can I use to set speed to 'OFF'?

I have configured a MQTT fan in Home Assistant and I can control the state and high, medium, and low speeds just fine by publishing the appropriate payload, but what payload can I use to turn off the speed?

The speed is initially in an ‘off’ state when the entity is initialized, but once I start using it the speed value is stuck on the last speed value when I turn off the fan. According to the documentation, I should be able to add ‘off’ to the speed array. However, when I do add an ‘off’ speed, the UI renders the speed as ‘false’. So the UI shows high,medium, low, and false speeds.

Despite the odd rendering in the UI, once the speed is added, I can select the ‘false’ speed in the UI and a payload of ‘False’ is published to the speed command topic and the speed’s state is reflected in the entity’s attributes. My problem, however, is that if I attempt to publish the same payload from the shell, the speed value is ignored by the MQTT Fan component and the speed state does not change.

So my main question is, how do I get this component to understand a { “speed”: “off” } state?