We've been using Google Family to monitor and restrict (when necessary) my daughter's mobile phone access for the last 2 years.
She will turn 13 next month, and I've just had an email from Google warning me that they'll be emailing my daughter directly to let her know she can take control of her account as soon as she's 13.
My daughter is pretty sensible, but I still don't think she's ready to set her own limits.
I had no idea about this when I signed up for it, anyone else?