From that link:
I would want to know where the data is coming from, as I don't think that's been officially released. In which case where is it coming from?
I suspect it may be from people contacting them and saying "my child is hospitalised", which is naturally going to increase as the website takes off.
I did look at the children in hospital thread before it was deleted. What I did notice was one person saying "no increase here" and nothing else was thanked by several people, whereas more people were very keen to disbelieve the twitter feed.
Realistically, it would be naïve to think there won't be an increase in children needing admissions. if more children have it, then more children are likely to need admissions. Plus you may have people who are hearing about the new variant and before would have said "doesn't effect children so they'll be fine", now will think "may be the new variant and that's far worse for children, must get them seen."
The question really is: are the admissions in line with what you expect or is there a significant increase?
I don't think it's necessarily easy to tell yet.