I really don't like the trend of looking at peoples bodies and using that alone to determine whether the amount they are currently eating is insufficient or excessive. The way someone looks just doesn't tell you that except for at the really extreme ends of obesity and starvation.
We don't know enough. Only she does, and whether she is acting upon what she knows in a way that's healthy, isn't something the commenters can know, either.
That does not look like 35kg to me, unless she is tiny af. Which she might be. The self harm scars in other posts obviously mean she's been not ok at some point, but may not necessarily mean she's still struggling now.
While I'm all for encouraging healthy living for everyone, that does not look like catabolysis, or like so much definition to be cause for worry due to a fat percentage approaching nothing.
People can look very skinny, or quite thick, without reaching a point that comes with significantly increased health risks. If nutritional needs are being met, muscle and fat mass can vary a lot without being unhealthy.
That's not to say you can go as low as you like as long as you eat right and avoid catabolysis, low body fat has some drawbacks of it's own, but they only kick in when approaching very low percentages. Fatty tissue serves many biological purposes and as such eliminating it entirely or pushing towards a very small number, has adverse metabolic, pulmonary and immunological affects. Above all, the nervous system is absolutely reliant of fatty tissue.