In file https://github.com/mozilla/pdf.js/files/5249872/product1.pdf, the fifth text widget has a default appearance using font F1 and this one is neither in DR nor in AcroForm but in AP::N::Resources.
if (this.data.pushButton) {
      return super.getOperatorList(
        evaluator,
        task,
        false, 
        annotationStorage
      );
    }
    if (annotationStorage) {
      const value =
        annotationStorage[this.data.id] &&
        annotationStorage[this.data.id].value;
      if (value === undefined) {
        return super.getOperatorList(
          evaluator,
          task,
          renderForms,
          annotationStorage
        );