Softboy

Softboi or soft boy: a less masculine boy who is described as "cute" based on their soft or gentle characteristics; mainly boys who express their softness a lot; can be used to describe trans men who do not subscribe to every element of traditional or mainstream masculinity.

It was coined by beyond-mogai-pride-flags in 2018, they also made the flag.

https://beyond-mogai-pride-flags.tumblr.com/post/176135234340/hey-this-is-gonna-sound-really-stupid-but-can-you