There's a couple interesting hypotheses in that article I wouldn't have thought of. However, I think they left out an obvious culprit, the lockdown meant that kids were home all day, which means less physical activity, and possibly a worse diet eating at home as well. One kid I know, used to be slim and running around all the time. I didn't see him for over a year after the pandemic began, gained 30 lbs and just played video games all day. His mom let him eat whatever he wanted, which was mostly junk food, and plenty of it.

Many children likely have a predisposition to developing diabetes, but they don't due to good diet and exercise. Take that away, and you'll see a significant rise in childhood diabetes. I'm not saying this is the sole cause of all these cases, but it also seems like a glaringly obvious omission.