Starting from August 19, 2021, the following features and capabilities will be changed or removed from the Adobe Acrobat online services:

• When you share a link to a document, the original file will be shared with the recipients instead of a copy. To make any changes to the original shared file, you must save a copy. This change is part of our ongoing development to support improvements in collaboration, security, configurability, and storage in the coming year.
• The ability to track participants’ status in the shared link will be removed. You will no longer receive notifications when shared files have been viewed or downloaded. You will continue to receive all other shared file notifications.
• Reminder notifications will no longer be available for shared workflows.
• When a new user shares a link, a recipient of the link not directly invited by the owner of the document via an Adobe email invite will not be added to the list of collaborators; they will also not be able to access the link from their Shared by others list in Document Cloud.
• In the Acrobat desktop application, you will not be able to sort files based on file size, file last accessed, or file type. The filter option will also be removed for Document Cloud files.

For more detail on Adobe announcement and detail of changes please read more here:

Acrobat online service feature changes