I googled it because I was confused too.

Meet the vulnerable (covert) narcissist

Often referred to as “covert narcissists,” the vulnerable narcissist (like the overt narcissist) has a narcissistic personality disorder.

However, vulnerable narcissists hide their narcissistic traits from the world, and unlike their overt counterparts, covert or vulnerable narcissists usually appear to be shy, reserved, and modest individuals. People with covert narcissism

Despite the mask they present to the world, vulnerable narcissists are chronically envious of others, have difficulty handling criticism, and lack empathy toward others. Woman with borderline personality disorder Covert narcissist

The covert narcissist is extremely sensitive to any slights in criticism and constantly compares themselves to family, friends, and co-workers.

People with covert narcissism usually prefer to be alone, mainly because of their hypersensitivity to other people’s judgments or perceived criticisms