Following the rename of SharePoint last week, we've been made aware that the "Quick access" links to SharePoint sites are currently not working and resolve to an error message. We have submitted a support ticket to Microsoft and they are looking into a solution.
In the interim, you can add a shortcut to your SharePoint site into your personal OneDrive. This will take you directly to the SharePoint site and allow access. Please see the attached guide for instructions.
We're sorry for the trouble and will update users when we get a resolution from Microsoft.