微软对 Office for iOS 的安装系统要求条件中，宣称只会支持 iOS 最新的 2 个版本。

当 iOS 的新版本发布时，微软将支持新版本和前 1 个版本。

iOS: Office for iPad® and iPhone® (including Outlook for iOS) is supported on the two most recent versions of iOS and iPadOS. When a new version of iOS or iPadOS is released, the Office Operating System requirement becomes the two most recent versions: the new version of iOS or iPadOS and the previous version.

微软官宣