You know what's also funny, the gorillas were different sizes because of sexual dimorphism. Decades later I was at a lecture about animal morphology and the lecturer mentioned that, among primates, humans are actually fairly androgynous. I think about that a lot too.
For all the cruelty we inflict on one another about it, an orangutan probably couldn't even tell you what the fuck we're talking about because male humans don't even have giant cheek flaps. Like the "angle measuring" bullshit that so-called "transvestigators" do would be absolutely hilarious to other primates because we invented this four hour long Voight-Kampff test since males aren't literally three times the size, with a nose like a tomato.
That sounds like a "premultiplied alpha" issue. Although I'm not familiar with this specific workflow, I always suspect premultiplied alpha issues when there's a halo like that. If there's an option try toggling it.