I wondered that myself. One possibility that occurs to me is that she got them from R2 when she visited Luke, since it's a fair bet Anakin had R2 make the original recordings, and he never seems to delete anything.
Failing that; maybe this T-6 was the specific one assigned to Anakin & Ahsoka (or I should say the only one left that he didn't crash) and Ahsoka *somehow* recovered it at some point in the last 30 years? That seems like a stretch though.
The only way I can kind of see it is the way Ezra tries to turn on the charm early on, but I just took that as a normal "young teenage boy meets slightly older pretty girl who's obviously way cooler than he is" reaction. It's just a reflex for him to show off, nothing actually romantic. Indeed, most of Ezra's relationships with the various Spectres revolve around the fronts he puts up, and how they gradually break down.
And if you chart the arc of Sabine & Ezra's relationship specifically; it goes from Ezra trying to impress her, while Sabine very much not taking him seriously, to them both having genuine respect for each other. While there's certainly a growing platonic affection there, the core of it is always about mutual respect.
