I have seen this claim before but I would really like the details. What are they doing? Physically present or engaging with kids?

As far as the UK goes I find this hard to reconcile with longer hours in school (breakfast clubs and after school things), huge growth in childcare businesses, etc.

I wonder whether the missing factor might be less informal childcare from family, so even if kids are spending more time with parents, they are spending less with family in total (therefore still getting less individual attention).

Both things could be true: It's possible that parents are more physically present (because they consciously decided to reduce hours or work from home) but are less mentally present (because a lot of that home time gets eaten by being on the phone or because working at home is still work).