A new Message Center Post has been published announcing the roll out of a change that impacts the SharePoint/OneDrive public search API
In order to protect user's private OneDrive content in SharePoint Search, we're making some changes to the way searches are handled in SharePoint Online. During November we will roll out changes to the default SharePoint Online search experience to make content from the user's own OneDrive for Business more clearly separated in the search results. With this change, the results will be clearly labeled as 'Results from your OneDrive'. An important reason for this change, is feedback from customers that returning search results from private content mixed with all other content may be confusing in an enterprise search result.
Starting in mid-November, in addition to the UX change, we will change the default scope for user queries issued via the Microsoft SharePoint CSOM and REST search API, in which private, non-shared results are filtered out of the tenant-wide experience.
For more detailed information see this article