I guess it’s a typo for “baby trans”, a sometimes-slightly-derogatory term (but can be neutral too) for people who only recently started transitioning or only recently realised they are trans ^.

Some people who’ve been transitioning for longer don’t find the kind of stuff they feel is often posted by “”“baby trans”“” people interesting or enjoyable or relatable. Or they just aren’t into online trans meme cultures, or several other things.