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);
    const dict = params.dict;
    const data = this.data;
    this.ref = params.ref;
    data.annotationType = AnnotationType.WIDGET;
    data.fieldName = this._constructFieldName(dict);
    data.actions = collectActions(params.xref, dict, AnnotationActionEventType);
    const fieldValue = getInheritableProperty({
      dict,
      key: "V",
      getArray: true,
    });
    data.fieldValue = this._decodeFormValue(fieldValue);
    const defaultFieldValue = getInheritableProperty({
      dict,
      key: "DV",