Sometimes index template change after node reboot

Hi everyone,

regarding to my needs i defined a index template with PUT _template API in kibana! on that template i set index pattern and specific index rollover alias.i send my logs from filebeat to logstash,,in logstash output i set elasticsearch and to my_alias index.my elasticsearch cluster has 3 nodes and logstash is installed on that nodes.sometime when i restart my nodes it seems that rollovered index use a different template...in another word the template change to something else..
is there anything wrong???

PUT /_template/my_template
{
    "order" : 0,
    "index_patterns" : ["my_index*"],
    "settings" : {
        "number_of_shards" : "5",
        "number_of_replicas" : "0",
        "index.lifecycle.name": "my_policy",
        "index.lifecycle.rollover_alias": "my_alias",
        "index.mapping.total_fields.limit": 5000,
        "codec": "best_compression"
        
    },
    "mappings" : {
      "date_detection": false,                     
      "properties" : {
        "timestamp" : {
          "format": "date_time||strict_date_time",   
            "type" : "date"
        },
        "@timestamp": {
          "format": "strict_date_optional_time",
           "type": "date"
        }
      }
      
}
}

What's the output from the _cat/templates?v API?

could you tell me what you are looking for???because the output is list of all templates which is too many

Anything that matches your pattern there.
Index temples to not just change after a reboot, something has to be changing it.

Thx alot... i will check that...another question where does the template data store??

In the cluster state.