What sort of things would require a Kindergartner to be held back?

We homeschooled in Kindergarten, but our situation no longer allows us to do so for the first grade school year. I feel like I wasn’t able to stimulate my little one as much as he needed during our year of homeschooling. So many things happened this year that I wasn’t able to *focus* on his schooling as much as I would have liked to. And I feel like he may be behind compared to other children his age.

What sort of things academically would require being held back?

Would it be bad to hold a child back in Kindergarten if the school/parent felt It necessary?

Thanks for any advice.