Because hidden and calculate questions do not display on a form, contents of the label field are not preserved. Viewing the survey records in the Survey123 for ArcGIS website or ArcGIS Online displays the question name at the column header for these types of questions. To force the column header of hidden and calculate questions to show a label, use the bind::esri:fieldAlias column in the XLSForm to specify a label.
This is outlined in the documentation Survey123 for ArcGIS: Esri custom columns - field aliases https://doc.arcgis.com/en/survey123/desktop/create-surveys/esricustomcolumns.htm#ESRI_SECTION1_9AC571BAFD664A07A383A8A6651849C4