What to say / not say to (adult) child that just got fired from their job

My (adult) daughter got fired from her job as a host at an upscale Italian food restaurant job today. Her call to me was very short. I started to ask what her boss said to her and she went off on a tangent about how the boss’ wife was at the cash register behind my husband when he said the food was “not authentic Italian food.” I don’t know if the wife heard the conversation but it’s very possible she did bc she was within earshot. I didn’t know it was the boss’ wife nor did my husband.
In any event, my daughter has been working there five months. But was told she was making “too many mistakes (presumably) on online orders.”
She’s an adult but she suffers from a mental illness that may in fact contribute to a loss of focus that could lead to mistakes at work. Yet, she is considered “high functioning” by her therapist.
My question is: How can I best support her? She’s not answering my phone calls. But she will eventually.