Please note that concurrency: 50 (in SsrOptimizationOptions) means that OptimizedSsrEngine will perform at most 50 parallel rendering tasks.
With the option reuseCurrentRendering enabled, it means: At most 50 different URLs can be rendered at once (regardless the number of parallel requests).
That implies: if you send parallel requests for 51 or more different URLs at once, then the reuqests for the 51st URL (and more) will fallback immediately to CSR. And it’s by design.
Moreover, it you enable debug:true, then you’ll see the console message CSR fallback: Concurrency limit exceeded

请注意 concurrency: 50（在 SsrOptimizationOptions 中）意味着 OptimizedSsrEngine 最多将执行 50 个并行渲染任务。
启用选项重用当前渲染，这意味着：一次最多可以渲染 50 个不同的 URL（不管并行请求的数量）。
这意味着：如果您一次发送 51 个或更多不同 URL 的并行请求，则第 51 个 URL（以及更多）的请求将立即回退到 CSR。 这是设计使然。
此外，如果您启用 debug:true，那么您将看到控制台消息 CSR fallback: Concurrency limit exceeded