Cluster round_robin did not balance every request from master to workers by numbers

[waltbest2]

Version

14.2.0

Platform

linux

Subsystem

No response

What steps will reproduce the bug?

I made a lot of request to test cluster，and every response time was nearly the same
，but I found that，sometimes requests were send to a worker in a period time.

It's not balance by request numbers.

How often does it reproduce? Is there a required condition?

No response

What is the expected behavior?

No response

What do you see instead?

No response

Additional information

No response