This new functionality was developed by the S2U a couple of years ago. It has been used in production in some institutions since then (2.7.2 and 2.9). It allows an instructor o ta to add the same feedback text to multiple students. It is handeled in the same way as the other option for multiple users: 'Select User(s) and Allow Resubmission'
This are the texts in english:
Select user(s) and write feedback in text area below:
Overwrite current feedback (NOTE: It does not override by default).
Return feedback to selected students now (NOTE: This opction only returns the feedback, if you wish to publish grades, you will need to clic on 'Release grades').