(TW: Genitalia mention, sex mention)
If someone treats lesbians as a separate human species that is completely different from all other human beings, that's a red flag.
This is pretty obvious when you are thinking about someone treating lesbians as inherently worse than other people - but this also includes treating lesbians as inherently better.
Lesbians are the only ones who actually truly love their partners? Lesbian relationships are the only healthy, non-abusive ones? Lesbian sex is the only clean, pure, loving kind of sex, all other kinds of sex are inherently dirty and traumatizing? Yeah, those are red flags.
These may sound like empowering statements - but when you look at them closer, the "logic" behind them is usually that dicks are bad and touching them makes you dirty. This is not only wrong and problematic for all the obvious reasons (gender essentialism, sex-shaming, transphobia...), it's also pretty insulting towards lesbians.
Lesbians deserve respect - only because they don't touch dicks? So, their worth is centered on their sexual history and habits? This is usually an attempt to invalidate trans lesbians but it ends up insulting cis lesbians as well. There's nothing empowering or feminist about reducing a woman to her sex life!
If you are a lesbian, then you have inherent worth and are deserving of respect. That's because you are a human being. You don't need to fulfill any other criteria for that.
You are more than your sexual past, you are more than your genitalia. Don't let anyone - right-wing or radfem - tell you your worth depends on the "pureness" of your sex life.