I have been told by a PPL converting to gliding that what happens at the top of a winch launch seems alarming because it has characteristics similar to sudden engine failure in an SEP. You will get used to it, and being briefed by an instructor experienced in converting PPL's to gliding would help.
In a normal winch launch, near the top, the angle of the cable pulling down is such that little net upward movement of the glider continues, and at the point of diminishing returns the winch driver reduces power to about idling. The glider pilot (flying) perceives this as a speed reduction, lowers the nose - from pointing up, to the normal glide angle (which is pointing a bit down) - and releases the cable.
If the pilot does not react to the reducing power, the cable goes slack and a clever feature of the hook releases ("back releases") the cable anyway, which makes a noise. The glider nose will then drop anyway, thought the pilot really should react by now!
Either of these, I am told, seems alarming. In fact, you soon get used to it.
During the launch, things seem to a newbie to happen so fast that the brain is several yards behind the glider. With experience, you become used to it and the separate phases of the launch become distinguishable and you get comfortable with it.