There is an interesting scenario where some users are unable to upgrade their Macs beyond macOS 10.12 Sierra for business reasons.
As of Office 2019 16.31, Sierra machines no longer receive Office 2019 updates. However, Office 2016 apparently continues to receive security updates on Sierra and older versions of macOS for the time being.
Are there any known issues with downgrading from Outlook 2019 to Outlook 2016 using an OLM archive file generated from Outlook 2019?
(Yes, we are aware that there are or will be growing security concerns with running Sierra. That is not my question. We are interested in being able to switch to Office 2016 16.16.16+ for the time being on Sierra machines while we balance risks against current business requirements.)