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.checkBox) {
      return this._saveCheckbox(evaluator, task, annotationStorage);
    }
    if (this.data.radioButton) {
      return this._saveRadioButton(evaluator, task, annotationStorage);
    }
    
    return null;
  }
  async _saveCheckbox(evaluator, task, annotationStorage) {
    const value =
      annotationStorage[this.data.id] && annotationStorage[this.data.id].value;
    if (value === undefined) {
      return null;
    }