If I saw a trans woman walking down the street I wouldn't go up to them and go "you are a man" that would be rude, and weird and yes transphobic. Just like I wouldn't interrupt a catholic mass shouting "it's just bread and wine you fools!"
But if there was a male in the women's toilets, or a rape crisis centre, or competing as a woman in the Olympics THEN it becomes appropriate to say "there is a man in the women's toilets, in the women's only rape counselling session, in the women's 100m final." then the differences between men and women are relevant. You can tiptoe around it with euphemisms but if anything that becomes more insulting. If someone was making me affirm that bread and wine could literally become Christ's flesh and blood I would find it necessary to say "it's just bread and wine"
If people really cared about the demonisation of trans people, they wouldn't be supporting an ideology that actively incentivises male sex offenders etc to identify as trans in order to get access to women's spaces. Or saying on behalf of their "trans friends" that women should accept males into changing rooms. Cos if I really did hate trans people that's what I would do!