Valgrind complaining in every use of QTextCursor:insertText

Geat

Every single time i use QTextCursor::Insert i get this from valgrind (and i can't ask for tech support directly because i use the open source liscence):

==3603== Invalid read of size 16
==3603==    at 0x204916A9: ??? (in /dev/zero)
==3603==    by 0x1122138F: ???
==3603==  Address 0x1122139e is 30 bytes inside a block of size 44 alloc'd
==3603==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==3603==    by 0x5C64B50: QArrayData::allocate(QArrayData**, long long, long long, long long, QArrayData::AllocationOption) (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Core.so.6.3.1)
==3603==    by 0x5C393F8: QString::reallocData(long long, QArrayData::AllocationOption) (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Core.so.6.3.1)
==3603==    by 0x555B079: QTextBlock::text() const (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x54C9C94: ??? (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x54C9F5E: ??? (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x5B9C60F: ??? (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Core.so.6.3.1)
==3603==    by 0x54D6662: QTextDocument::contentsChange(int, int, int) (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x54EE9BB: QTextDocumentPrivate::finishEdit() (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x54D3023: QTextCursor::insertText(QString const&, QTextCharFormat const&) (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x54D3167: QTextCursor::insertText(QString const&) (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Gui.so.6.3.1)
==3603==    by 0x4D18630: ??? (in /home/anyuser/Qt/6.3.1/gcc_64/lib/libQt6Widgets.so.6.3.1)

Code:

bool CodeEditor::AddCloseBraceAndChangeIndent()
{
    auto cursor = textCursor();

    cursor.beginEditBlock();
    cursor.insertText(QChar('}'));

    cursor.movePosition(QTextCursor::PreviousCharacter, QTextCursor::MoveAnchor, 2);

    if(cursor.block().begin().fragment().text()[cursor.positionInBlock()] == QChar('\t'))
        cursor.deleteChar();

    cursor.endEditBlock();

    return true;
}