Under normal circumstances, Microsoft provides regular updates to Microsoft 365, which means that it will always be supported as long as it is kept up to date, but there are some cases that fall under the exception. That is Windows 7 (specifically SP1), Windows 8.1, and Windows Server 2008 R2 editions, these obsolete systems will no longer receive Microsoft 365 support from Microsoft (including other Office 365 editions).
As for why it is January 10, 2023, because Windows 7 and Windows Server 2008 R2 have long ceased to be supported, but Microsoft still provides ESU extended support to paying enterprise customers, and extended support ends on this date.
After the operating system completely ceased support Microsoft continues to provide Microsoft 365 support has not been too meaningful, after all, Microsoft is mainly for enterprise customers before.
According to Microsoft’s announcement to January 10, 2023, Windows 7/8.1/Server 2008 R2 will not get any security updates, even for paid ESU users, and similarly, Microsoft 365 will not get any updates, users who want to use new versions of Microsoft 365 or get security updates must If you want to use the new version of Microsoft 365 or get security update support, you must upgrade to a supported operating system.
The minimum supported operating system is Windows 10 LTSB 2015 Enterprise Edition or Windows 10 20H2 Consumer/Enterprise Edition and Windows Server 2016 Edition.
