30% of children in Germany have mental issues due to the coronavirus-measures
Citation needed. The only thing I could find is this[1], which is just nonsense. It's probably similar to the much more sensible numbers from the UK, maybe a bit better since, so far, Germany hasn't had a lockdown as strict as the UK.
https://www.bbc.com/news/health-55863841
This is a typical situation when the cure (coronavirus measures) is worse than the disease.