This issue is related to MDL-70585. When a filename has some unicode characters (for example an emoji), some combination of unarchiving tool / OS can't unzip the file.

Steps to reproduce:

1. Login as admin
2. Navigate to Courses > Download course content in site administration
3. Enable Download course content feature available
4. Create a new course, setting Enable download course content to Yes
5. Add a File resource to the course:
   • Name: File with non ASCII characters
   • File to upload (attached): _MoodleTrelloPortadaReference🥵.png_
6. In the course Actions menu select Download course content
7. Extract the downloaded archive using the unzip command on a terminal

   • unzip downloadedfilename.zip

8. Open the index.html file in the extracted location
9. Follow the File with non ASCII characters (File) link
10. Click on _MoodleTrelloPortadaReference🥵.png_
11. Confirm you can't see the image