Microsoft issued relevant instructions again on Wednesday, recommending that companies and users currently using Office 2016/2019 migrate to subscription-based Microsoft 365 Apps as soon as possible.
Microsoft said that Office 2016/2019 users will no longer provide support for Microsoft 365 connections starting October 10, 2023. Users will still be able to access Microsoft 365 after that date, but there may be various scenarios such as unstable connections.
Microsoft made a clarification in a statement sent to foreign technology media ZDNet in August last year, and the attached content as follows:
We do not prevent supported Office 2016/2019 from connecting to Microsoft 365 cloud services. However, as announced in April 2017, we plan to end mainstream support for Office clients connecting to Microsoft 365 cloud services. This means that as we make updates to Exchange Online, SharePoint Online, and other Microsoft 365 services, they won't be built around the inherent limitations of legacy, perpetual Office clients that have outgrown mainstream support. Users' connections will not be hindered, but they may not get full functionality from the cloud service. Over time, they may encounter unexpected problems.