Change in SharePoint Links

Hi All,

Today I noticed that when sharing a document from document library,

URL is generated something like

XYZ.sharepoint.com/:w:/s/sitename/EQMfnd73HhjkfdHVPv7GLJOkRDznDagfdgdH83

Where as previously it used be something like 

XYZ.sharepoint.com/sites/sitename/_layouts/15/guestaccess.aspx?docid=hfjksd39fkJKGfjd&authkey=fhjkd79kjhfkjdkky6876jn

Does anyone know if anything has been changed or anything has been changed on my site? If its on my site, What can I do to get back the links with /_layouts/15/guestaccess.aspx

Thanks a lot