Welkom !
You misinterprete that flap. It is not intended as protective cover, but as means to enlarge the metering range or to rather split a metering range in two, so that more likely a metering can be done at substantial swing of the needle.
Thus we are speaking in your case about 2 different set-ups: single and dual-range.
Both do not only differ by that flap with with a hole, but more likely in the circuit already and in the case of the flap of a second marker to set the calculator at.
Here a photo of the dual range version:
You can see the flap (swung down to partially cover the light meter)
And a red and a black marker at the static dial.
In normal operation you twist the calculator knob until at the black&white scale part the number you read at the needle is set at the red static marker. Then at L-designated marker at the movable (DIN) dial you read the Lichtwert, you need to set the shutter accordingly.
In case of a subject in very bright light, you flip down that cover and then set the number you read at needle now instead at the black static marker.
In your case there should be no hinge for that flap and only one marker at the static dial. Otherwise indeed that flap is missing.
I hope this helps.
I never got in hand this camera, but I am sure I deduced things right...