An interesting memo on this issue from a CPA in 2014.  It recommends Box 3 of Form 1099-MISC.  It also says that the charitable deduction would not be allowed if any expenses are reimbursed, even if only partially.  Six months after the 1099's have been filed, I think you're going against the wind by arguing "wrong form."  Report it as other income and deal with IRS if you must, if a CP-2000 follows.  And try to resolve the issue with the payer organization before 2023 ends.

file:///C:/Users/Bob/Downloads/Memo-TaxabilityofHostFamilyPayments.pdf