> Following the steps of a previous study with this same dataset (measuring baseline associations only [13]), we categorized screen time here into three major groups: (a) Watching (1 + 2), (b) Socializing (4 + 5 + 6), (c) Gaming (3).

So that's why they described it as " ocial media, text, and video chat". Their data comes from the ABCD study. I didn't look much further. https://abcdstudy.org/