It’s rough even for English as a first language speakers. The alt-right, conservatives and transphobes in general have these little subtle words they use to signal their transphobia to each other and signal their intent to troll or that their real intentions while pretending to debate in earnest. “Biological gender” is a more frequent one but they get waaaaay more subtle.

One you see in the UK that is SUPER subtle is transwoman or transman. Properly speaking trans is a separate adjective so it modifies the noun. “The woman is trans” in effect. By removing the space in trans woman they sort of signal their intent and allegiance by creating a whole new noun as in : “That’s not a woman that’s a transwoman” it’s so subtle it could just be accidental and leaves plausible deniabillity for the user of the term… but trans folk get used to seeing these little cues that signal that the writer or speaker is getting their talking points from very specific hostile sources. Language has been very weirdly weaponized but when you understand what is happening it can help you figure out the diehard transphobes who are wasting your time and good faith from the people actually just properly duped by the misinformation brokered by those with malicious intent.