That isn’t a render glitch, it’s a skinning glitch.
Your vertex groups need to overlap in order to make smooth bends. Also you need to line up the bones with your mesh.
I fixed the left arm. As you can see, it bends smoothly with no overlaps, unlike the right arm.
This is the left upper arm fix. Notice the position of the bone is changed. With such a blocky mesh, the bone is best placed with the head at the top of the block and the tail centered in the joint. The vertex group is shown selected, and includes ALL of the joint vertices.
This is the vertex group for the Lower left arm. In order to have smooth bends, ALL the joint vertices are included in BOTH vertex groups.