The bug

When using the spyglass in third person, it is entirely parented to your head and unmoving. The arm tries and often fails to attach to it. Your arm should make contact with it at all times.

Screenshots
   

Java

I tested in Java, and it does seem that it's also always parented to the head, but it moves forward and backward to match the hand, and the hand does a better job at lining up with it.