QSyntaxHighlighter does not apply capitalization with QTextCharFormat::setFontCapitalization

QSyntaxHighlighter does not apply capitalization with QTextCharFormat::setFontCapitalization.
This is apparent in the example provided. The example is edited version of the Qt's highlighter example.

How to replicate the problem:
1. Build and run the provided example project with Qt version 5.15.0 or 5.15.2 or 6.0.0.
2. Write for example: "QMenu" into TextEdit.
3. The other properties of QTextCharFormat are visualized, but capitalization won't be visualized.

4. One can also test the commented code in line 141, only underline takes effect. So, capitalization won't be applied using QFont::setCapitalization either.

When tested QTextCharFormat::setFontCapitalization worked in general level, so the problem seems to be specific to QSyntaxHighlighter.