This "low power mode" is a myth, the brain pulls a pretty constant amount of power (about 20% of metabolic energy), and most power isn't consumed by the action potential/neurons firing, but rather in keeping the neuron ready to fire.

And the regions involved in the default mode network are actually some of the metabolically most active regions in the brain, involved in memory consolidation, future simulation, theory of mind, and self-narrative; among other things.

I would postulate that it's even worse than this, given that default mode network activity is proven to be essential for a healthy mind. This is when engage in useful thinking even when we're not "doing anything".

I think screen activity/tiktok keeps us in some kind of purgatory where we can neither fully engage nor fully disengage.

This framing seems like the correct one, but I think that just like being physically sedentary leads to weakness of muscles and joints and health problems, so being mentally sedentary could also lead to a mind that is weakened in the long term, though the weakness could likely be reversed with exposure to exercise.

the article does note:

"The researchers caution against reading the deactivation as evidence of impaired cognitive function. As they put it in the paper, “this deactivation should not be interpreted as a failure of cognitive control capacity.” Instead, the team argues the pattern likely reflects an adaptive shift toward low-effort, automatic processing during passive, low-conflict viewing."

my take: if the study authors could qualify a subject's liked videos, they could qualify a subject's liked activities, and study activation thresholds prior to and post short form content exposure. this would provide a better substrate from which to draw such conclusions.

but I don't need a study to tell me that short form content fries the brain ... it fries my brain!