The nether portal overlay is rendered completely opaque when using spyglasses while standing inside of nether portals

The Bug:

The nether portal overlay is rendered completely opaque when using spyglasses while standing inside of nether portals.

Steps to Reproduce:

1. Construct a nether portal and obtain a spyglass.
2. Switch to survival mode, go inside the nether portal blocks, and use your spyglass.
3. Look at the nether portal overlay that's rendered on your screen.
4. Take note as to whether or not the nether portal overlay is rendered completely opaque when using spyglasses while standing inside of nether portals.

Observed Behavior:

The nether portal overlay is rendered completely opaque.

Expected Behavior:

The nether portal overlay would not rendered completely opaque and would combine with the spyglass overlay.