I see a lot of teenagers with mental health issues as part of my job. There has been a definite increase, this is due to a combination of factors. Covid certainly didn't help. But that's because it exposed and intensified the issues that were already brewing and had been for some time.
Social media has a part to play. "Normal" teenage struggles, embarrassments, disappointments and friendship issues are now played out publicly on social media so become blown out of proportion and are more difficult to 'bounce back' from. Kids who struggle socially don't get a break from those struggles because it's 24/7, whereas pre-internet they would have just had to deal with it at school.
Services that used to support families with social issues have either been cut altogether, massively reduced or have huge waiting lists. Poverty, unstable housing, parental conflict, antisocial behaviour in communities, drugs and alcohol...all these things impact the wellbeing of parents and children. Services cannot focus on prevention or early intervention because they don't have the resources so families have to be in crisis before they get any help and even then they have to wait. Many of the kids I see with significant MH issues don't respond to therapy because their home lives are chaotic, stressful and unpredictable so no amount of talking is going to change that.
There is also a tendency to medicalise normal human emotions. Genuine MH issues absolutely have increased, no question. But so has self-diagnosis based on being exposed to a huge amount of unhelpful content about MH on Tik Tok and Instagram. Often Year 11 and 13 kids will tell me they "have Anxiety" and then when you actually unpick this with them the only thing they feel anxious about is their upcoming exams. But now its "anxiety" not exam nerves. Instead of being upset by an argument with a friend or a break up they're "traumatised" by it. They will tell me they "have anger issues" when actually they're feeling angry about something very specific and completely justified. I'm seeing this from parents too, not just the kids themselves. It worries me how many kids, and parents, think that if a child isn't happy and relaxed all the time something must be very wrong.