I know this is you venting, but it's because they're white, and in this racist settler colonial society, whiteness always comes first regardless of their professed ideology or whether they belong in any other marginalized community. A white fascist cishet man and a white socialist trans woman are just two white people when push comes to shove. I suspect you found this out the hard way.

I only trust white people who either:

1. Have biracial kids with a POC partner (although they're plenty of white fetishists and some biracial pairings like white dudes with Asian chicks are so filled with fetishists that I no longer find this reliable)

2. Exclusively hang out with POC as the token whitey

If a white person does both, then there's a good chance their anti-racist views are genuine.