So can you explain what’s with the anime girl roman memes with all the sexism and racism?

As I said below

Mostly it’s just absurdist jokes and memes by a Filipino Romaboo with a terminal case of Horny.

Centurii-chan is internet-overdosed, that's for damn sure, but unless "Being terminally horny" is sexism, I don't think I see it. As for racism, there are certainly some edgy jokes, and Centurii-chan doesn't always take racism as seriously as they should, but I don't think I've seen anything that's degrading towards PoC. Which, itself, would be a little weird, considering the artist is, themselves, most likely a PoC.

I also don’t get the fetish that the people over in non credible defence have either. War, guns and killing glorified and memed. So bizarre.

Many people in NCD, or at least the original (especially pre-Ukraine War) NCD, were vets or involved in the defense industry at some point in their lives. Some were bitter, some were cheerfully detached, but in both cases, humor over the absurdity of the military and fascination with military engineering were uniting features. Many of them were... bizarrely knowledgeable on military engineering and specs, both modern and historical. An attraction to those with a certain hyperfixation, one might say.

Military engineering is impressive and militaries the world-round are likewise full of fascinating absurdities - interests I share with that original demographic, even though I have never been a part of the defense industry or in the military.