I wasn't talking about manga, but about the perception Japanese people at large, even outside of media, have of lesbians. See note at the bottom here: https://dynasty-scans.com/chapters/liberty_ch15#5
It's not specific to manga. It's a more general stereotype.
I mean, people who straight-up assume that lesbians are horny and sleep around would generally behave in two ways. They would a) look down on lesbians and not read media about them at all, in which case series like these would be irrelevant, or b) see this as erotic and actively seek out manga featuring lots of hot lesbian sex, like this one, which, as I've pointed out, is a fairly progressive depiction of lesbians exercising sexual agency and indulging in their desires, outside of this chapter (heck, the endgame is our protag reconnecting with the girl she had a crush on). Either way, I don't see lesbians as a whole suffering because of Asumi-chan is Interested in Lesbian Brothels!.
If anything, I'm pretty sure the main demographic for this manga are lesbians who want to read something funny, sexy and heartwarming instead of Blushing Schoolgirl Story #991, so while you claim that 'lesbians are horny and sleep around' is a stereotype, the vast majority of lesbians who actually read it would see it as a USP (if nothing else, the folks on this forum seem to like it). So from a representational perspective, it captures a side of lesbians that's not often covered with the appropriate nuance and empathy, and from an entertainment perspective, it establishes an identity and caters to a market. It'd be different if the manga stated that all lesbians love to cheat and sleep around, because that would be malicious- in this case, the horniness is constrained to an escort service and the women who peruse it (possibly because they can't easily have relationships in ordinary society). It'd be weirder if they didn't have tons of sex.
Lastly, the example you've cited states that the Japanese see lesbians as people who often cheat. Putting aside the accuracy of this claim or the sources that the scanlators used to come up with it, I'd like to point out that this manga doesn't even feature any cheating or infidelity. I get criticizing the non-con part, because that made me wince a bit as well, but the rest of your criticisms are misplaced at best and actively unrelated to the topic at worst.