I'm so happy to be having this conversation with you, because it's a real issue. There is a lot of writing about transphobia within gay spaces -- which of course, is a real problem many of us have encountered many times over. But there is comparatively very little writing about homophobia and lesbophobia in trans spaces. And having been in a lot of trans spaces over the years, I have seen and heard a lot of flippant, glib homophobia.
In particular, I see a lot of young nonbinary and trans people talking about how cis gay men are incredibly privileged, shallow, oppressive, etc etc. A lot of young trans people (and young queer people in general) talk about gay men as if the 1980's never happened. And there is a lot of drilling into our heads, within trans spaces, that we can expect cis gay people to reject us and not see us as the people and genders we are. Yet my actual experience in the world has been that cis gay people have been very accepting and warm to me for the most part, and curious to learn more and to join our communities together in better ways.
This dynamic of mistrust also seems to dovetail with ageism a lot. Lots of people in queer and trans circles don't seem to recognize what older gay men (and bi men) went through during the AIDS epidemic's height, and how much badass political organizing work so many of them did. Instead they all get written off as this rich insulated oppressor class...which is just factually incorrect. I correct it whenever I encounter it but it's a game of wack a mole.
Then you add into the mix that some transphobic and homophobic bigots are actively trying to sew discord between our two groups, by obsessing on things like genital preference and other rhetoric that is designed to provoke fights, when actually most of us are on the same page on those issues. Everything gets so heightened and every fight becomes symbolic, and we talk to one another less and less.