This is an ad-hoc data lookup — the `ad-hoc tidb-p99-breakdown` recipe is exactly right for this. Let me run it directly.根据 `ad-hoc tidb-p99-breakdown` 配方的权威返回结果，所有关键信号均缺失（主延迟指标、5 个节点级补充信号、2 个集群级信号全部 missing）。按规则，证据不足不可猜测。

```json
{
  "cluster_id": "10748116073341772391",
  "window": {
    "start": "2026-07-21T03:00:00Z",
    "end": "2026-07-21T03:05:00Z"
  },
  "evidence_sufficient": false,
  "cluster_avg_tikv_grpc_request_handle_p99_s": null,
  "cluster_avg_pd_tso_request_handle_p99_s": null,
  "top_nodes_by_avg_p99_latency": []
}
```