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.
getArray: true,
    });
    data.defaultFieldValue = this._decodeFormValue(defaultFieldValue);
    data.alternativeText = stringToPDFString(dict.get("TU") || "");
    const defaultAppearance =
      getInheritableProperty({ dict, key: "DA" }) ||
      params.acroForm.get("DA") ||
      "";
    data.defaultAppearance = isString(defaultAppearance)
      ? defaultAppearance
      : "";
    const fieldType = getInheritableProperty({ dict, key: "FT" });
    data.fieldType = isName(fieldType) ? fieldType.name : null;
    const localResources = getInheritableProperty({ dict, key: "DR" });
    const acroFormResources = params.acroForm.get("DR");
    this._fieldResources = {
      localResources,
      acroFormResources,
      mergedResources: Dict.merge({
        xref: params.xref,
        dictArray: [localResources, acroFormResources],
        mergeSubDicts: true,
      }),
    };
    data.fieldFlags = getInheritableProperty({ dict, key: "Ff" });
    if (!Number.isInteger(data.fieldFlags) || data.fieldFlags < 0) {
      data.fieldFlags = 0;
    }
    data.readOnly = this.hasFieldFlag(AnnotationFieldFlag.READONLY);
    data.hidden = this._hasFlag(data.annotationFlags, AnnotationFlag.HIDDEN);