As a trans man, I do admit this makes me incredibly uncomfortable, it triggers me, even... But I'm willing to learn. I'm trying to understand and interact with he/him lesbians.
Please understand that for us trans men, this is very uncomfortable because we associate he/him pronouns with men and trans men. For many of us, it seems like mockery, disrespecting us and our struggles. Women using he/him pronouns while still seeing themselves as women and are lesbians makes it seem to us that our live-long struggle, especially those with gender dysphoria, means nothing if anyone can just use whatever pronouns they please without seeing themselves as the gender those pronouns are meant for.
As I said, I'm willing to learn, but please also understand where we come from. I don't agree with the hostility from the trans community because I know how it was like back then when nobody understood us and disrespected us. But we need to talk more. We need more communication. I hope I can learn more in the future.