It's e.g. not uncommon for people to go into some form of denial of their (new/worsens) mental illness, it they are simple not aware that a mental illness can have given effects.

This makes it super hard to differentiate between something causing mental illness and that something in some way making people being diagnosed with it.

E.g. the current works situation makes it much simpler for people to get depression and anxiety without being infected by Covid-19, but due to the circumstances if someone got a new (or worsens) mental illness and covid in 2020 it's likely that they will diagnosed the illness after having had covid even if it came from the world situation not the covid virus directly.

Example Unrelated to covid: I got diagnosed ~3years after it (slowly) started to mess up my life, but that was when it started to noticably affect my life. As far as I can tell before that I had it in a mild version for like and addition 7-10 years.

So the time where sunshine is diagnosed as mentally ill isn't necessary at all related to when that person got mentally ill.