There’s a few groups of Christians who have zero problem with trans men being men and trans women being women… but if those men aren’t the primary breadwinners of the house and take a strict hand in ensuring his family is godfearing, if those women aren’t submissive and obedient homemakers, then they’re not real men/women for the exact same reason they’d call a cis man or woman “not real.”
They’re the same people who ask gay and lesbian couples who wears the pants in the relationship because all that matters is that one person is in the “man” role and one is in the “woman” role, and even then if you’re not in a man/woman relationship that’s on thin ice but if you’re both going to church together than that’s tolerable sometimes.
I legit have had a person be accepting of me being trans and then be furious I was a lesbian because “how are you going to say you’re a woman and then not do a woman’s job for your husband?” Another person didn’t even assume that, they just said “oh so that’s why you never got married you need a husband not a wife that makes sense.” Like I was too stunned to speak!
They’re the ones who get extra upset about nonstandard pronouns or really anyone who’s any flavor of nonbinary because “if you’re not man or woman, then what role?” It’s TIBP: Trans Inclusive Biblical Patriarchy. They care entirely about traditional family values and nothing else. That doesn’t mean they’re super accepting of trans people or queer friendly or anything, do not mistake these people for allies, they just see the world in a very particular way and if you conform to that worldview they’ll be able to ignore that you’re trans and just focus on your gender as you are.