Both this article and the one it references have pictures showing her wearing a distinct Tesla "Get Amped" t-shirt while posing in or in front of a Tesla car. I first thought these were actual Tesla promo shots but the photo credit indicates they were taken for the Guardian.

This crosses the line between calling out a problem and directly attacking a brand.

I'd be interested in seeing how her allegations hold up in court but the way the Guardian presents her case makes this less about the alleged problems and more about herself vs Tesla. Even if she hadn't known this would result in her being fired, the Guardian must have seen it coming a mile away.