### Environment

* Dubbo version: 3.1.0
* Operating System version: xxx
* Java version: 1.8
* Istio version: 1.13.2

### Steps to reproduce this issue

1. 运行Istio+proxyless [demo程序 ](https://github.com/apache/dubbo-samples/tree/master/dubbo-samples-xds )，启动后consumer能正常访问provider。
2. 扩大provider副本数为2， consumer无法感知到新增的provider节点，新增的provider节点也没有收到consumer的请求。
3. 删除provider对应的k8s service（取消服务注册），consumer没有感知到服务变化，仍然可以继续调用provider。
4. 恢复provider service后，重启consumer实例，consumer才可以正常发现2个provider节点。

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package org.apache.dubbo.registry.xds.util.protocol;
import org.apache.dubbo.common.logger.Logger;