secondary sources (updated as found):

https://www.ofcom.org.uk/research-and-data/media-literacy-research/childrens#accordion__target-108180
- An OFCOM report on the social media habits of Children.

https://www.harvard.co.uk/six-insights-childrens-media-habits-ofcoms-children-parents-report/
- A Harvard insight article into potential changes in media habits in children, which also views a parental perspective.

https://www.theguardian.com/media/2019/jan/04/screen-time-not-intrinsically-bad-for-children-say-doctors
- A study which suggests that screen time isn't too bad for children, which is an interesting outlook on the topic.