No, QoS is about the way mqtt messages are handled/stored in the mqtt broker.
With a mqtt message with topic yicam/motion_start you should be able to start the motion detecting in the camera. Such a message can easily be configured in pimatic.
For that you need to configure the camera with this topic for the action ‘switch motion detection on’
My suggestion would be to configure the following
switch camera on = topic: yicam/motion_start
switch motion camera off = topic: yicam/motion_stop
motion detected = topic: yicam/motion_detection