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.
constructor(params) {
    super(params);
    this.checkedAppearance = null;
    this.uncheckedAppearance = null;
    this.data.checkBox =
      !this.hasFieldFlag(AnnotationFieldFlag.RADIO) &&
      !this.hasFieldFlag(AnnotationFieldFlag.PUSHBUTTON);
    this.data.radioButton =
      this.hasFieldFlag(AnnotationFieldFlag.RADIO) &&
      !this.hasFieldFlag(AnnotationFieldFlag.PUSHBUTTON);
    this.data.pushButton = this.hasFieldFlag(AnnotationFieldFlag.PUSHBUTTON);
    this.data.isTooltipOnly = false;
    if (this.data.checkBox) {
      this._processCheckBox(params);
    } else if (this.data.radioButton) {
      this._processRadioButton(params);
    } else if (this.data.pushButton) {
      this._processPushButton(params);
    } else {
      warn("Invalid field flags for button widget annotation");
    }
  }
  getOperatorList(evaluator, task, renderForms, annotationStorage) {