Following the fix for MC-276674, specially rendered elements on entities such as spiders, endermen, and phantoms no longer render using additive blending, making their eyes appear completely opaque while invisible as opposed to having a "glowing" effect on objects behind them.

24w39a:

24w38a:

In the following screenshots, you can also see that the objects behind the enderman's eyes are faintly visible in 24w38a, however they are not in 24w39a:

24w38a:

24w39a: