Single right quotation mark read as "???" - Why?

I am parsing XML files with embedded HTML using the XML2 file type in Studio 2021. In some instances, the character U+2019, which is in the text as normal character (not as HTML entity ’) is displayed in the edito as "???":

This is how it looks in Notepad++:

The source file is UTF-8 encoded.

Why is Studio not displaying the unicode character as a normal U+2019 single right quotation mark? For this string, I am using a customized version of the HTML5 ECP, but that should not matter, should it?

Daniel