TLDR: It's most likely non-viral and unrelated to alcohol or environmental factors. Can't be Covid-Vaccination related because the kids are too young. Most likely candidate is Ad41 which was found in half of the kids.
As per the article, non-viral hepatitis is cause by things others than viruses.
Related: https://www.medrxiv.org/content/10.1101/2022.04.28.22274443v...