Nah.

It’s a tribalism impulse, most of the time. They’re parroting what some influencer or other jerk said.

You’re thinking of the distinct “I’m definitely hetero, bro,” which is the fragile masculinity thing.

I don’t think it has anything to do with masculinity, women say it too.
I think It is 100% envy. There is something that they are repressing because they have been told it is bad, and they see gay people, who they have also been taught are bad, “getting away with it”, even flaunting it.