Single node serving more traffic than other nodes in the pool.

can you confirm how you "measure" the traffic here ?

is it number of connections (TCP) number of requests per second ? are you using HTTP 1.0, 1.1, 2.0 ?

are you servers using the same stack ?

Some TCP behaviours on your servers can cause one to close connections faster as an example.

Do you have OneConnect activated on serverside ?

sorry for not really answering your question but there are so many parameters to take in account before answering, i prefer having more details before providing some valid points to help you identify the reason of this traffic difference.