If the cylinder is the issue it would most likely be an issue all the time once the piston seal failed. The start would be fluid level check. On that car the pump should be in left quarter behind the wheel up high. The solenoid on the pump assembly could have some little piece of debris that sticks ...

little tidbit: the solenoid opens the fluid flow path to and from cylinder. The pump motor runs CW and CCW to determine whether it goes up or comes down. The flow reverses "polarity" and that determines whether the cylinder gets fluid applied to base to extend and open which sucks fluid fr...

There is an assist motor and cable the finishes the close of latch and begins the opening due to the hydraulic cylinder having poor leverage when the tailgate gets down. What you see is expected if the hydraulics don't take over once the latch open/close assist step completes.