From Microsoft Corporation
MC213970, Stay Informed, Published date: May 21, 2020
We’re expanding the types of files that your users can share with downloads blocked (read-only).
This message is associated with Microsoft 365 Roadmap ID 64278.
When this will happen
We’ll be gradually rolling this out in late May, and the rollout will be completed by late June. How does this affect me?
Users can currently create SharePoint and OneDrive sharing links that block the download of Office files. This sharing link allows recipients to read the file but not download it.
This update expands the list of supported file types to include PDF files, images, and audio files, for example. This update is in response to customer requests.
The experience of creating a read-only/download-blocked sharing link is unchanged. Users must uncheck “Allow editing” for the “Block download” toggle to be accessible.
What do I need to do to prepare for this change?
Administrators can control whether the “block download” setting appears only for Office files or whether it allows additional file types by editing the BlockDownloadLinksFileType setting in the Set-SPOTenant or Set-SPOSite PowerShell cmdlets. The options are “enable for only Office files” or “enable for all supported files” (default).
You might consider updating your user documentation and training materials. Learn more about sharing files and folders.