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() {
    this.width = 1;
    this.style = AnnotationBorderStyleType.SOLID;
    this.dashArray = [3];
    this.horizontalCornerRadius = 0;
    this.verticalCornerRadius = 0;
  }
  /**
   * Set the width.
   *
   * @public
   * @memberof AnnotationBorderStyle
   * @param {number} width - The width.
   * @param {Array} rect - The annotation `Rect` entry.
   */
  setWidth(width, rect = [0, 0, 0, 0]) {
    if (
      typeof PDFJSDev === "undefined" ||
      PDFJSDev.test("!PRODUCTION || TESTING")
    ) {
      assert(
        Array.isArray(rect) && rect.length === 4,
        "A valid `rect` parameter must be provided."
      );
    }
    
    
    if (isName(width)) {
      this.width = 0;