Encountered an unsupported variant tag '' on 'Analysis.INormalizer', which could not be deserialized

[feherbbj]

Elastic.Clients.Elasticsearch version: 8.13.12
Elasticsearch version: 8.12.2
.NET runtime version: 8.0

If you inser the following schema, then use "client.Indices.GetAsync(new GetIndexRequest(Indices.Index("analyzer-fail")));" It will throw an exception "Encountered an unsupported variant tag '' on 'Analysis.INormalizer', which could not be deserialized."

PUT analyzer-fail
{
  "settings": {
    "analysis": {
      "normalizer": {
        "keyword_lowercase": {
          "filter": [ "lowercase" ]
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "id": { "type": "keyword" },
      "keyword": {
        "type": "keyword",
        "normalizer": "keyword_lowercase"
      }
    }
  }
}

Expected behavior
This used to work in 7.x