As you may be aware a new SharePoint Online (SPO) administration portal has been on preview for quite some time now.
This new administration portal experience for SPO is now going to become the default administration portal for SharePoint Online.
You will still have the ability (for some time??) to switch back to the previous (and well known) administration portal by using the Classic SharePoint admin experience link available in the left side menu
You can also set back the classic administration experience as the default by turning off the Default admin experience setting from the Settings menu (this is the setting which is going to be turn on by default with this update)