Limit in index document filter using Roles

In a role I added a document filter on an index like below::

{
    "bool": {
      "filter": [
        {
          "terms": {
            "data_stream.dataset": ["1","2","3","4","5","6","7","8","9","0"]
          }
        }
      ]
    }
}

When using this role in Discover, I notice that only max 8 are used?

Can somebody confirm this limit is inplace?

KR Henk