As a matter of interest, not all Catholics think body and soul are separable in the way gender-identity-type souls are taken to be by much gender ideology.
Thomas Aquinas was explicit about this. (Summa Contra Gentiles (II.69), "The soul and the body are not two actually existing substances ...")
René Descartes argued explicitly against the Thomists ('Schoolmen') of his time about this. (And he was afraid of these Schoolmen; he knew about Galileo's brush with them.) Many people now are Cartesian dualists, including all the 'gender-identitists', even if they don't really understand the issues,.
(Although not most queer theorists/post-structuralists. They have an interesting, even crazier, take on the whole business that melds not at all with the gender-identity-as-soul idea, though both sides of that divide, once they realise this, keep it quiet (for political reasons) how incompatible their views are.)
Mainly - oversimplifying perhaps a little - the Thomist v Cartesian distinction goes back to Aristotle v Plato. Plato (and the neo-Platonists) thought a soul could exist without a body ('ante rem' or 'before the thing'), whereas Aristotle (and the Thomists/Schoolmen) decided that souls, as the 'form' of their bodies, could only exist 'in re' ('in the thing') - as an essential part of the (equally essentially embodied) man or woman.
(This is why 'the resurrection of the body' is part of the Christian creed; it harks back to Aquinas' view of body and soul as essentially inseparable parts of a human, so that it would not make sense to have a human soul existing in heaven without its body.)
What is the relevance of this to debate about gender identity and trans people?
Well, over long years we have learned to live with people who don't agree with us about souls (and other things). We no longer allow one particular set of beliefs to be promulgated as part of a state religion; we don't (for the most part) torture and kill those we disagree with about ante rem or in re realism and so on.
And we don't allow teachers in schools to give our children one particular view of all this, although we may encourage some "Here are some things people believe, children ...", for children to compare and contrast with what their own parents and families believe (or know) to be the case.
Except that, regarding trans souls, people have started again with "This is how things are; you must believe ...". They have picked one of the more foolish of the available metaphysical pov, indeed: a naive Cartesian dualism-without-god that cannot be true. But that's not the most important thing, imo.
Let them believe what they want. Laugh at them behind their backs; smile to their faces. Let them be. But keep them away from our children and legal systems. Please. This is one religious war we really do not need.