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.quadPoints === null) {
      return false;
    }
    if (this.flags === 0) {
      return false;
    }
    return this._isPrintable(this.flags);
  }
  /**
   * Set the contents.
   *
   * @public
   * @memberof Annotation
   * @param {string} contents - Text to display for the annotation or, if the
   *                            type of annotation does not display text, a
   *                            description of the annotation's contents
   */
  setContents(contents) {
    this.contents = stringToPDFString(contents || "");
  }
  /**
   * Set the modification date.
   *
   * @public
   * @memberof Annotation
   * @param {string} modificationDate - PDF date string that indicates when the
   *                                    annotation was last modified
   */
  setModificationDate(modificationDate) {