I have 5 servers on cluster, but the data are not use symmetrically :
ELS01 : 62%
ELS02 : 50%
ELS03 : 69%
ELS04 : 76%
ELS05 : 86%
I wonder why this seems problematic to you. This is perfectly normal Elasticsearch behavior. It does not balance by disk space, rather it uses the low and high watermarks to ensure that no node gets to a full disk.
As long as your workload is served well, this is no problem. Perhaps there is an underlying symptom you are chasing?