This is because there's a difference between how gay men and lesbian women are treated. And that's because there's a difference in how men and women are treated. All of this is caused by sexism and the subjugation of women under patriarchy.

Without getting too much into it, the main problem society has with gay men is because of their attraction to other men. The main problem society has with lesbians is their refusal to have sex with men. Obviously, the reverse is true to an extent, but look at the main criticism being leveled at lesbians: man-hater, because we don't want to fuck men. Lesbians are far more likely than gay men to be correctively raped as a form of conversion therapy.

Gay men get along much better with women because there hasn't been numerous instances of women correctively raping gay men to cure them of their homosexuality. Yeah, straight women can be really disrespectful in gay men's spaces. But from what I can tell, women are still way more respectful of gay men's boundaries than men are of mine. Pretty much every lesbian I know have had instances of men trying to fuck them despite being told no, men treating their sexuality like a fetish. I've personally had a man expose his penis to me after sneaking into a lesbian-only space.

The thing that a lot of non-lesbians don't really understand is that lesbians need to be able to say no. No as in never. There's been awful histories with bihet women trying to sneak their boyfriends into lesbian spaces, force their boyfriends onto lesbian women. Sometimes it's the woman's personal fantasy, usually it's as a "special treat" to their man or a hail mary to save their shitty relationship. I'm sure there has been instances of bihet men sneaking their girlfriends into gay spaces and trying to force their girlfriends on gay men, but I've never heard it with any sort of frequency. Usually, the man is going behind their gf/wives' back to cheat. By and large, men's boundaries are far more respected than women's. By and large, society cares more about men's pleasure than women's.

Lesbians aren't "defending" the lesbian label because it is "cool". That's a common mistake non-lesbians make because non-lesbians don't see it from our perspective and they don't care to. Bihet women especially view it as a form of "stinginess" or "gatekeeping". We "defend" it because it's part of saying no. It means no men. Not now, not ever. Bihet women who call themselves lesbians are undermining that.

Also, "straight" transwomen who try funny shit usually gets murdered. Not so much for agp trash.