No, there is no source, because it's an overinflated nothingburger created to stir up controversy and division.
blind3rdeye
I use to think about this a lot, and would constantly try to fix it - trying to look like I wasn't just playing with my dick while doing it.
But now that I'm older I realise most people know clothes do this, and that it doesn't really look like a boner anyway. And people generally aren't looking at me wondering if I've got a boner, and they probably don't care if I do unless I'm also staring at them or something. .... So now I just worry about accidentally staring at people. (And my eyesight isn't great, so it isn't always easy to tell.)
I don't know how many users reddit has, but it is a lot more than lemmy. Lemmy is quite small in terms of number of users.
But I think focusing on relative numbers of users is a mistake. Forty thousand people is still a lot of people. And we can see that it is enough people to create a vibrant community with a steady stream of good content and conversations. So the fact that it is small compared to other social media is not really relevant, in my opinion. Having a thousand times more users doesn't make things a thousand times better - that's for sure.
(That said, I do think its worth noting if the number of users is going up or down... because if there was a significant downward trend, that would be a bad sign.)
Don't be a dick. The dev is not transphobic, and you know it.