It is not just children being overcounted. I think it is every category that they claim to be tracking.
Case in point, on the death stats...
https://www.fema.gov/press-release/20210629/fema-amends-covid-19-funeral-assistance-policy
“The new policy provides applicants, as well as medical authorities, coroners and jurisdictions, flexibility to attribute a death to COVID-19 without amending the death certificate.”