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.
return null;
  }
  /**
   * Reset the annotation.
   *
   * This involves resetting the various streams that are either cached on the
   * annotation instance or created during its construction.
   *
   * @public
   * @memberof Annotation
   */
  reset() {
    if (
      (typeof PDFJSDev === "undefined" ||
        PDFJSDev.test("!PRODUCTION || TESTING")) &&
      this.appearance &&
      !this._streams.includes(this.appearance)
    ) {
      unreachable("The appearance stream should always be reset.");
    }
    for (const stream of this._streams) {
      stream.reset();
    }
  }
}
/**
 * Contains all data regarding an annotation's border style.
 */
class AnnotationBorderStyle {