When _index_template is set _template is ignored

[Petr.Simik]

I created default _index_template to add attribute to settings for hot nodes
since I set this parameter all _templates are ignored.
There is some incompatibility between _index_template and _template

do I have to migrate all _templates to _index_template?
or can I stay with _template?

PUT _index_template/default
{
  "priority": 0,
  "template": {
    "settings": {
      "index": {
        "routing": {
          "allocation": {
            "include": {
              "data": "hot"
            }
          }
        }
      }
    }
  },
  "index_patterns": [
    "*"
  ],
  "composed_of": []
}