With final_pipeline and a pipeline specified, the final pipeline appears to be running twice with index date math processor

[ed.yoo]

Testing on 7.6.2, the following code works fine in using a final_pipeline and a pipeline for the index. Using the same code and updated index template code, it actually appears to run twice on 7.15.2 (and 7.16.0).

The following example appends a value and the value shows up 2 times rather than just once after running through the pipeline

PUT _ingest/pipeline/test-final-pipeline
{
  "processors": [
    {
      "append": {
        "field": "pipeline",
        "value": "completed"
      }
    }
  ]
}

PUT _template/test-template
{
  "index_patterns": [
    "test*"
  ],
  "settings": {
    "final_pipeline": "test-final-pipeline",
    "number_of_shards": 2
  }
}

POST /test-1/_doc
{
  "time-field": "2021-02-10T12:02:01.789Z",
  "CONTENT": "blah1"
}

PUT /_ingest/pipeline/routing-test-pipeline
{
  "description": "Time series DAY pipeline",
  "processors": [
     {
         "date_index_name": {
             "field": "time-field",
             "index_name_prefix": "test-",
             "date_rounding": "d",
             "index_name_format": "yyyy-MM-dd"
         }
     }
 ]
}

POST /test-1/_doc?pipeline=routing-test-pipeline
{
  "time-field": "2021-02-10T12:02:01.789Z",
  "CONTENT": "blah2"
}

The next example shows that trying to edit a field name, if you add ignore_missing: true, the field name is already renamed:

PUT _ingest/pipeline/test-final-pipeline
{
  "processors": [
    {
      "rename": {
        "field": "CONTENT",
        "target_field": "MALCONTENT"
      }
    }
  ]
}

PUT _template/test-template
{
  "index_patterns": [
    "test*"
  ],
  "settings": {
    "final_pipeline": "test-final-pipeline",
    "number_of_shards": 2
  }
}

POST /test-1/_doc
{
  "time-field": "2021-02-10T12:02:01.789Z",
  "CONTENT": "blah1"
}

PUT /_ingest/pipeline/routing-test-pipeline
{
  "description": "Time series DAY pipeline",
  "processors": [
     {
         "date_index_name": {
             "field": "time-field",
             "index_name_prefix": "test-",
             "date_rounding": "d",
             "index_name_format": "yyyy-MM-dd"
         }
     }
 ]
}

POST /test-1/_doc?pipeline=routing-test-pipeline
{
  "time-field": "2021-02-10T12:02:01.789Z",
  "CONTENT": "blah2"
}

Is there anything missing in these tests or could Issue #69727 or Issue #75047 be related to causing this to run twice when using the date math processor for the inde?