I think you're simply experiencing a power differential. You are at the mercy of the institution, and you're scared that the email will mean bad consequences for you.
That framing resonates a lot. It really does feel less about the content and more about the imbalance — someone else has information or authority over you, and you don’t yet know what it means for you.I hadn’t thought of it explicitly as a power differential before, but that explains why the anxiety hits before any facts are known.