Inquiry about deep stable JSON stringify utility in Effect library

class GetInvoicesRequest extends S.TaggedRequest<GetInvoicesRequest>("GetInvoicesRequest")("GetInvoicesRequest", {
  failure: S.Union(XeroError, XeroBadResponseError, XeroNoRefreshTokenError),
  success: GetInvoicesResponseSchema,
  payload: GetInvoicesPayload.fields
}){
  [PrimaryKey.symbol]() {
    return `GetInvoicesRequest:${JSON.stringify(this)}`
  }
}