Steps to reproduce:

1. Use either a Moodle 4.0 instance or the patch provided in MDL-76309
2. Create an assignment with feedback types "Offline grading worksheet" and "Feedback files" enabled and group submission disabled
3. Create a submission for the student A
4. Visit the assignment as a teacher
5. Click on "View all submissions"
6. Click on "Download all submissions" (top right of the page) with "Download submissions in folders" (bottom of the page) enabled
7. Unzip the file.
8. Add a file in the folder belonging to student A (e.g. a simple text file)
9. Add a sub-folder "Test" in the folder belonging to student A
10. Add a file to the sub-folder "Test"
11. Re-ZIP the contents and upload the modified ZIP file choosing "Upload multiple feedback files in a zip" in the "Grading action" dropdown
12. Confirm the file upload
13. Re-Upload the same ZIP file (from step 11) choosing "Upload multiple feedback files in a zip" in the "Grading action" dropdown
14. You will see "Modified feedback file..." twice