This is some information regarding update MC139171 published May 17, 2018 from Microsoft

The Office start pages for Word, PowerPoint and Excel are being updated. This feature will be rolled out soon.

How does this affect the User?

Users will see an updated Start experience for both Desktop (Windows) and Web versions of the Office apps (Word, PowerPoint and Excel) These updates will show a new experience that allow you to see documents important to you more easily, create content quickly and get updates on activities in your document.

We’ll be gradually rolling the web experience out to Targeted Release customers in mid-May, and we will start the roll out to Standard Release customers in mid-June. The roll out will be completed worldwide by the end of June.

We’ll be rolling out the Office desktop (Win32), in our May update for the Office 365 ProPlus monthly channel. If you are on semi-annual channel for updates, you will receive these at a later date. To determine which channel you are configured for, please read the overview of updated channels for Office 365 ProPlus.

There is nothing you need to do to prepare for this update except for perhaps user training and notifying your helpdesk.