Upstream monitoring abnormality

[xiaofanshifu]

os: centos7
nginx version: nginx/1.18.0

node1: tomcat 1
node2: tomcat 2

Why is my node 2 closed and there are still requests and responses?

In fact, I can no longer access node 2, There should be no requests and responses. When I visit nginx in the browser, I also display the web content of node 1. In fact, I don't visit node 2.