No Japanese character support in participants list PDF download

Description:

Users with Japanese characters in their name appear as boxes in a downloaded PDF of the participants list.

Steps to replicate:

1. Users>Accounts>Add a new user
2. Set Firstname = テスト, Lastname = ユーザー
3. Enrol the user in a course
4. Go to Participants list
5. Tick to select テスト ユーザー
6. Click With selected users>Portable Document Format (.pdf)
7. Open the PDF and view

Expected behaviour:

テスト appears in Firstname column

ユーザー appears in the Surname column

Actual behaviour:

Boxes with question marks appear in place of the Japanese symbols

Additional notes:

I have tested opening the same PDF in Chrome, Edge, and Adobe Acrobat Reader DC. All three of them display the symbols as boxes.

Other download formats e.g. CSV, Excel and Word all seem to display the characters fine.

NOTE: This is not a duplicate of MDL-65080 which was resolved by applying the Japanese locale to the site. The issue in this tracker item occurs regardless of whether or not the locale is installed and is replicable on demo.moodle.net.