@john Top reason is that Pleroma had a prominent TERF involved with development for a while, so the Pleroma community self-selected for people who are ok with transphobia. (Discussing this often attracts sea lions who claim that technology is neutral, bemoaning cancel culture.)
For people who like the technology but want a community that might enforce a code of conduct, consider the hard fork Akkoma instead: https://coffee-and-dreams.uk/development/2022/06/24/akkoma.html