Home Assistant prevents the removal of one MQTT-discovered entity from erasing all the other components of its device. The correction also protects devices when software cleans up old discovery messages after changing how it describes the device.
A device remains while it has supported enabled or disabled components. Removing the entire device still clears it; removing only an entity in Home Assistant can allow it to return when the device publishes its configuration again. To keep that component away, disable it or remove it from the device’s discovery configuration.