genderswaps are when you take, say, a male character and make them female. that in itself is fine if you’re headcanoning a character as trans (such as the princess marco headcanon from svtfoe), but taking a cis dude and making him a cis girl says that gender = sex and by extension, ignores trans people + implies that we aren’t our actual gender, but the gender we were assigned at birth, even if we’ve transitioned.