I've seen a couple of flakes on CI, all of the form

[ RUN ] IpVersions/RoleBasedAccessControlNetworkFilterIntegrationTest.Allowed/IPv4
test/extensions/filters/network/rbac/integration_test.cc:92: Failure
Expected equality of these values:
1U
Which is: 1
test_server_->counter("tcp.rbac.allowed")->value()
Which is: 0
[ FAILED ] IpVersions/RoleBasedAccessControlNetworkFilterIntegrationTest.Allowed/IPv4, where GetParam() = 4-byte object <00-00 00-00> (54 ms)

@yangminzhu would you be up for taking a look? Perhaps the counter() should be a waitForCounter variant?

https://github.com/envoyproxy/envoy/blob/master/test/integration/README.md#reproducing-test-flakes may help reproducing/verifying