QT_UNICODE_LITERAL() and QStringLiteral(u"stringLiteral") is the 'u' needed anymore?

[Tummon]

The docs reference using QStringLiteral() along with the UTF16 literal 'u'
https://doc.qt.io/qt-6/qstring.html#QStringLiteral

As well a Note: Some compilers have bugs encoding strings containing characters outside the US-ASCII character set. Make sure you prefix your string with u in those cases. It is optional otherwise.

But in "qtbase\src\corelib\text\qstringliteral.h"

#define QT_UNICODE_LITERAL(str) u"" str

Is used exclusively in both Qt5.15 and Qt6.4

Is prepending the 'u' necessary anymore for any use case?