Transgynephobia a form of transphobia, specifically the fear or aversion towards trans women. This phobia can be caused by negative experiences with trans women, like being bullied or attacked by them and believing trans women are bad people. Religion and societal experiences and expectations may also be a potential cause of transgynephobia.
Laverne Cox
Propaganda spread online, such as harmful stereotypes, can also be a cause for this phobia, like the belief that specifically trans women will sexually harass your kids.