Yes. That was part of one of the recent executive orders he signed [1] which was dictating not only that care for transgender individuals in the military should cease but also that expressing a different gender identity was not compatible with being in the military. It's not even particularly vague about it. The military issued guidance against the executive order to not take adverse action, essentially only adopting the bathroom bill portion of it [2].

[1] https://www.whitehouse.gov/presidential-actions/2025/01/prio...

[2] https://storage.courtlistener.com/recap/gov.uscourts.dcd.276...