I'm certain it's not a vt.
It looks like a fighter... perhaps? I've seen some pictures and some plakat-fighters look like that and some strange plakats, so I dunno.
One of my Bettas, Pearl, sold to me as a female decided to go male also, with fins growing rapidly, flaring all the others and becoming territorial. Pearls tail type, as far as I know, is roundtail or fantail. YOur fish looks very similar so I reckon you have the same tail type