The reversing valve has four oil ports. After reversing, all ports are P-A and B-T, and the rotating motor is P-A, so it must be B-T, that is, port B returns oil. If the oil cylinder connected to port B loses pressure oil, it will definitely drop.
Let's add another reversing valve, one for the motor and one for the oil cylinder.
Or add a stop valve (ball valve) at port B. If you don't want the oil cylinder to fall, close the valve and open it when the oil cylinder needs to move. Don't forget when operating.