Qt Quick Calendar: 1st row sometimes contains only days from the previous month

import QtQuick 2.15
import QtQuick.Controls 6.3
import QtQuick.Window 2.15
import QtQuick.Layouts 1.15

Window {
    id: window
    width: 640
    height: 480
    visible: true

GridLayout {
        columns: 2
        
        DayOfWeekRow {
            locale: cal.locale
            
            Layout.column: 1
            Layout.fillWidth: true
        }
        
        WeekNumberColumn {
            month: cal.month
            year: cal.year
            locale: cal.locale
            
            Layout.fillHeight: true
        }
        
        MonthGrid {
            id: cal
            month: Calendar.January
            year: 2023
            locale: Qt.locale("en_US")
            
            delegate: Text {
                text: model.day
                color: model.month === cal.month ? "black" : "gray"
            }
            
            Layout.fillWidth: true
            Layout.fillHeight: true
        }
    }
}