I'll bet that if LW's kid was a trans boy instead, and got the same gift, LW would say that a plush toy is girly and it must be Ashley's way of getting at LW, around whom the whole world revolves.

I worry for Isabella. Her mother's going to push her into being super super girly, because she seems to think that that's the "right" way to be a trans girl. I suspect there's unacknowledged transphobia behind this on LW's part; a lot of cis folks think someone's only "really" trans if they embody every social convention/stereotype about their gender. (Of course it's possible that Isabella is super super girly, but her being perfectly happy with a basically gender-neutral gift and not wishing for a girlier one suggests not.)

ETA for clarity: Isabella should be able to be as girly or not girly as she wants to be. The problem is, there's a lot of pressure on trans people, from the social expectations of strangers to actual gatekeeping in order to access medical treatment, to behave in the most conventional way for their gender. Otherwise, consequences can range from misgendering to denial of medical transition to literal violence. LW seems to have bought into this (with the extra bonus fuckery of assuming that anything her sister does is really about getting back at LW), and that's really not good for Isabella.