I've run into this as a gay transman, too. So you definitely are not alone in your frustration! Given that I haven't been able to be approved for mastectomies, this is counted as a strike against me as much as my weight in the gay community. I've seen transmen far heavier than me get approved for that in California, but everywhere I've turned, I am told to lose weight.
The problem, aside from fatphobia? I have polycystic ovarian syndrome, which in my case makes losing weight extremely difficult. Yet because I'm fat and unable to get mastectomies, it often means even in LGBTQ+ spaces I'm invisible to most gay, bi, and pan guys, and I'm written off as "you'd be perfect if you were a 'normal' size".
The fatphobia was depressing in guys who claim to "not care" what their beloved looks like when I was a 16 year old tomboy, and it's still depressing as a nearly 35 year old transman.
Unfortunately, I am a very plain-faced person, my teeth aren't great because I was born massively premature, so my enamel is practically nonexistent, and due to poverty as well as having a disabled, widowed, mother, I had to step down from college to take care of her when her health took a steep decline, I've never been able to afford a car, and I can't afford to move out - people use finances, teeth, and status to shun and reject others as much as weight, without ever bothering to find out WHY the person is in that situation.
The fatphobia only adds to the stress of dating on that front for me.