Below are links to the new features that were added since GP2016.
GP2018: https://docs.microsoft.com/en-us/dynamics-gp/whats-new/version-2018
GP2018 R2: https://docs.microsoft.com/en-us/dynamics-gp/whats-new/version-2018-r2
GP 18.2: https://docs.microsoft.com/en-us/dynamics-gp/whats-new/version-october-2019
GP 18.3: https://docs.microsoft.com/en-us/dynamics-gp/whats-new/version-october-2020
GP 18.4: https://docs.microsoft.com/en-us/dynamics-gp/whats-new/version-october-2021
The most common reason for updating is for the new 1099-NEC form which is a 3-per page form for calendar year 2021. However, there are a number of online services that can be used to produce 1099s. I’ve included links to a few that various GP partners recommended last year.
Tax Forms Store (comes bundled with the Office Depot brand 1099 forms)