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.
const value =
      annotationStorage[this.data.id] && annotationStorage[this.data.id].value;
    if (value === this.data.fieldValue || value === undefined) {
      return null;
    }
    let appearance = await this._getAppearance(
      evaluator,
      task,
      annotationStorage
    );
    if (appearance === null) {
      return null;
    }
    const { xref } = evaluator;
    const dict = xref.fetchIfRef(this.ref);
    if (!isDict(dict)) {
      return null;
    }
    const bbox = [
      0,
      0,
      this.data.rect[2] - this.data.rect[0],
      this.data.rect[3] - this.data.rect[1],
    ];
    const xfa = {
      path: stringToPDFString(dict.get("T") || ""),
      value,