Which direction are they going in?  Was 1099, now W-2 or the other way around?

Be aware of this IRS position from the 8995-A instructions (page 2):

https://www.irs.gov/pub/irs-pdf/i8995a.pdf

If you were previously an
employee of a business and continue to provide substantially the
same services to that business after you’re no longer treated as an
employee, there is a presumption that you’re providing services as
an employee for purposes of section 199A for the 3-year period after
ceasing to be an employee. You may rebut this presumption on
notice from the IRS by providing records such as contracts or
partnership agreements that corroborate your status as a
nonemployee.