I do worry about this actually, as my MC is 15.
I guess there's murder (and mass murder), bullying, stress, depression & anxiety, mental/physical abuse, sleep & eating disorders (this is tricky), poisoning, enslavement, torture, suicide (implied, won’t be shown), psychological manipulation, grooming (not the sexual kind), discrimination, religion (and religious cults), politics & war, violence and death... lots of death.
There are some nice things too though.