"On Thursday, officials revealed that in seven of 102 cases involving children under 5 separated from their guardians, the adult was determined not to actually be the parent."

So ok, you're only slandering ~95% of those 102. If you don't like the term "slander" how about "generalisation" or "prejudice".

Forgive me if these words have negative connotations, or "trigger feelings" - but what term would you use, to describe declaring 100% of a group to have attributes that only apply to - by your very own research - 5% of that group?