Virtual Stick Commands are control signals constantly send from the remote controller to the drone (stick simulations), and feedback signals constantly send from the drone to the remote controller.
They depend heavily on a Constant Good control signal.

DJI Drones that are build for the DJI Fly App are controlled by VSC during waypoint missions. (Mini-1-2-SE, Air-2-2S & Mavic-3)

Older DJI drones are not, they fly by themselves.
They also have an extra AIRCRAFT Setting:
“Exit Waypoint Mission on Signal Loss: Off/On”

Waypoint Missions are NOT drone depended.

When a mission is used with an older drone, it gets uploaded to the drone the moment you hit Start. When the upload is completed, the drone will take off and flies the mission fully autonomous.
If you would turn off the remote controller after take off, the drone is still able to complete the entire mission when ‘AIRCRAFT’ setting ‘Exit Waypoint Mission on Signal Loss’ is set to ‘Off’.
When ‘AIRCRAFT’ setting ‘Exit Waypoint Mission on Signal Loss’ is set to ‘On’, the drone will initiate the set ‘Signal Lost Behavior’ i.e. ‘Hover’, ‘Landing’ or ‘Return to Home’…

When the same mission is used with a newer drone (VSC-drone), it’s controlled by VSC the moment you hit start and takes off immediately.
The ‘AIRCRAFT’ setting ‘Exit Waypoint Mission on Signal Loss’ is not available with these type of drones (VSC-drones).

Every 10th of a second (I believe it is) Litchi sends a control signal with tasks to the drone, so the drone knows what to do, then the drone sends a feedback signal to Litchi, so litchi knows if the drone executed these tasks and were executed correctly, now Litchi can workd out the next set of tasks to send to the drone.

When either of these signals do not arive at their destination, even for 1/10 of a second, trouble starts, like strange behaviour of the drone.

When this interruption takes too long (Signal lost), the mission is aborted and either ‘Return to Home’, ‘Hover’ or ‘Landing’ will initiate depending on the AIRCARFT Setting ‘Signal Lost Behavior’.

Don’t confuse Control Signal with Video Feed Signal.

Have a look at this video (starting at 2:30)