There was a mod that made it so the 70% black humans in Stellaris were white, it got banned.

This one will forever be fucking retarded.

Melanin exists because of unprotected solar radiation intensity experienced on planets. A spacefaring race that lives behind ship/station bulkheads that may also include protective shields will inevitably trend towards no melanin [and anti-weapon shields are a thing in Stellaris so even the base game lore supports it - along with some mods that specifically give you protective shields to shield from harmful space radiation].

It's how any living organism works, it doesn't waste energy if it can get away with it. Just because you can promote melanin production doesn't mean you will, hence suntans. We develop them because we expose our skin to increased solar radiation and the body goes "OH FUCK!" and attempts to not potentially die of skin cancer and other issues. Remove the stimulus and after long enough the body stops producing it because it doesn't need to anymore.

It's the basics of the biological "energy budget". You don't spend energy on something you don't need as from an evolution POV it's a waste of resources which are meant to be spent on 2 things.

1. Fucking

2. Living long enough to fuck

That's it. That's the purpose of life. To reproduce, be that sexually or otherwise, the reason an organism exists is to propagate and create offspring.

I can rant about this for fucking hours going into variances in energy budget spending but it's tangential for the most part since the main point is mentioned above. Describing how some aphids put more energy into flight strength over reproductive capability is just one example of many that detract from the significance of how fucking retarded the Paradox devs are in addition to massively incompetant at times given how often they manage to repeatedly break their games when they reintroduce old bugs from years ago back into live patches.