The person in question also looks like she’s in her early 20’s. She had a chronic condition where she was basically in a waking coma but wasn’t “experiencing” stuff for a decade so it’s as if time had jumped from her POV because she has no memories of that period.
This gap is so disorienting for her that she identifies her age as 22. Being told her actual birth year causes confusion and distress, as it clashes with her sense of time and personal experience.
Nothing wrong with hanging out with people that are a different age to you.
I was part of a board game group where the ages ranged from 20 through to 45.