No it means that literally nothing else makes the kid behave this specific way. It's a catatonic state where the kids senses are clearly overwhelmed, they do not move at all(!!) and their responsiveness degrades to near zero. After screen time the otherwise normal kid starts to behave erratically, seems like they have the need to compensate with more movement for the monitoneless time. If you try to talk about what they saw it becomes clear that they failed to process what they saw and multiple days and multiple hours of talking would be needed to wade through something as simple as half hour of David Attenborough animal documentary.

Wether enough scientific fact has been gathered to understand the inner workings and circumstances are irrevelant, the cognitive weight of TV exist as a matter of fact.

Now there are of course difference between TV and monitor and screen time. What causes the problems are TV like stuff - passive, movie-ish information. Drawing lines in paint or typing buttons to see them appear on notepad is definetly another thing - the information flow and actions there are controlled by the kid and there is another huge difference if the parent is there explaining. Not the monitor itself is the problem, but the absolutely overwhelming quantities of raw information which designed specifically to catch and hold an adults attention. Kids simply have no means to absorb or escape it.

On my experience kids over 4-6 years starts to absorb some of the information and kids over 8 can sit through a disney movie with sufferable consequences.