The fear of being judged by others is quite common and is at the root of many social anxiety disorders. A character in this situation may feel extreme anxiety about people watching, evaluating, and finding fault with them (whether this is really happening or not). This fear may arise when the character is meeting someone new, speaking in public, going on a date, answering a question in a class or business meeting, or even carrying on a conversation with someone at the store. When this fear goes unchecked, it can create tremendous anxiety and cause the character to avoid the situations that might bring it on.

Shyness or introversion
Seeking to conform to societal norms
Agreeing with whatever's being said in a conversation
Avoiding busy places
Posting only carefully edited photos on social media that cast the character in the best possible light
Not engaging during meetings, classes, or group outings
Giving non-committal or vague answers
Trying to appear smaller (crossing the arms, standing at the edge of a room, etc.)
Difficulty making eye contact with others
Having a small friend group
Becoming tongue-tied when someone's attention turns to the character
Being highly observant
Taking pains with their appearance
Closed-off body language (shoulders hunched, hair hiding the face, etc.)