In version 0.4.3a while running Iris, parts with the "Glowing Eyes" effect enabled will not correctly render. Sometimes these cubes will render underneath all cubes, but sometimes they will correctly render in front of the cubes. However, the glowing cubes don't use additive blending, and they appear similar to normal cubes.

Rendering behind:

Rendering in front:

Expected behaviour (Iris disabled):

Additionally, the gizmos and cube outlines will always render behind the model in the editing window. Unlike in game, I haven't experienced them rendering in front of the model.

Current behaviour:

Expected behaviour (Iris disabled):

The issues are clearly a problem with specifically Iris. I ran Minecraft with only CPM, Sodium (which is required for Iris to function), and the fabric API, and the issue arises. When Iris is removed, the issue disappears.