PDF space export does not render/display non english letters/umlauts for parent page titles properly

Issue Summary

In Confluence 7.19.x, the non-English letters/characters (umlauts like ä) in parent page title are not rendered/displayed properly while exporting a space as PDF. The child page titles and page content are rendered properly even if they have non-English letters in them.

Note: This bug doesn't impact 8.x versions (tested 8.9.0 and 8.5.8)

This is reproducible on Data Center: yes

Steps to Reproduce

1. Setup Confluence 7.19.x (tested in 7.19.20 & 7.19.21)
2. Create a parent page with title containing non-English letters (like ä)
3. Create a child page with title containing non-English letters (like ä)
4. Confirm that parent page title has non-English letters. Reorder pages from Space tools if needed
5. Go to Space tools > Export > PDF > Normal Export > Export > Download PDF

Expected Results

All non-English letters should be rendered correctly in the PDF generated after space export

Actual Results

The parent page title containing non-English letters are not rendered correctly whereas child page title and page content are displayed properly. Reference screenshot below

Workaround

Upgrade to Confluence 8.x versions.

Alternatively, reorder pages so that pages with non-English letters are child pages in a space.