Strange as this might sounds the split on one side of the rubber rain guard is not a fault but manufactured this way. Here’s the info explaining why we do it:
The binoculars can be attached to the strap on either or both sides by sliding the strap through closed loops. When both loops are used, the rainguard will fall onto the eyepieces every time the binocular hangs down. This can be convenient in some cases, such as very wet or dusty/windy conditions, and when storing the binoculars in the case, but it usually slows down removing the rainguard and impedes viewing. To solve this problem, most manufacturers have a solid loop on one side of the rainguard and a split loop on the other.
Below is an image showing how the neck strap can be connected to the binoculars and the rain cover if needed. Note the split part is not connected to the neck strap.