Anxiety can be triggered by anything and it’s one of the most common mental health issues. I’ve found it takes a very intentional practice to deal with it as it comes up for myself.
The first step to overcoming it is to simply notice when it’s happening.
I’ve found it useful to change the internal narrative from “I’m feeling anxious” to “I’m experiencing anxiety”. This detaches the feeling from your character. You don’t associate yourself as being anxious but recognize once in a while it invades your thought process.