During December 2021 there will be an IRD ( Interim Release Download ) for Sage 100 2019. This update will include “1099 Form changes for the tax year 2021 (Applicable for Accounts Payable module only, to support Form 1099 Tax Reporting)” and as noted the IRD ” Requires Sage 100 2019 PU5 (6.10.5) “.
During the month of September updates for Sage 100 v2020 and v2021 appear to have included the above noted 1099 changes. There was no product update released for Sage 100 v2019 which is likely why Sage has scheduled an IRD for only version 2019.
For more information please see this Sage knowledgebase article – Sage 100 Update Release Schedule.