It's not just the lesbians, it's the fact that they present a world that all of the Righty-Tighty dingleberries like SheRa fag fear: A world where not only is the gay wild and free, it doesn't even come up as a source of conflict or drama once.
There's a non-binary character, but non of that character's conflicts or issues stem from their identity as a non-binary person. A character has two-dads, but that has nothing to do with why he has a strained relationship with them. It's all played straight, no second glances or double-takes.
Endangered gaybashers like the kind that seek refuge-in-anonymity on this board can't stand the idea of gay being presented as normal, so they hound this show harder than any others, even shows with active lesbian relationships like The Owl House, because it's something they can just jerk off to and forget about.
She Ra lives rent-free in the mind of /pol//co/ not because it's a good show, or because it has some kind of acclaim, but because they cannot abide by a show that doesn't present Gays as mentally aberrant circus-folk like their pastor taught them.