How to display the German Umlaute like, ä, ö, ß in invoice template

Summary:

Unable to display the German Umlaute like, ä, ö, ß in invoice template

Content (please ensure you mask any confidential information):

We have a requirement for an Invoice Template that needs to display special characters like ä, ö, ß. But when we click the View Image from the transaction page, they are not being displayed properly.

Is there a way to properly handle this in the RTF template? Kindly advise.

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):

Screenshot of the Invoice template:

Screenshot of the output: