In the end, labels are about community and they’re meant to make the person using them feel more comfortable. So honestly anyone with a strong connection to a label and the associated community can use it, we aren’t cops to gatekeep. Also, transmascs aren’t necessarily trans men so that fits under the lesbian umbrella already, but also trans men can use the label if they have that connection to the lesbian community, probably through identifying as a lesbian before they realized they were trans