Field value uppercase on old cluster, lowercase on new

[Ron_Hay]

I'm having an issue with an old cluster (7.2.1) having some term fields being in uppercase, but a new cluster (7.5.2) having the same terms, from the same docs and synonyms file, being lowercase. Here are the most relevant settings/mappings (I just copied from old to new)

Old cluster:

              "filter" : [
                "trim",
                "lowercase",
                "hpo_autophrase_synonyms",
                "hpo_entity_extraction_synonyms",
                "keep_synonyms"
              ],
              "tokenizer" : "standard"
            }
                "hpo_terms" : {
              "type" : "text",
              "term_vector" : "with_positions_offsets",
              "eager_global_ordinals" : true,
              "analyzer" : "hpo",
              "fielddata" : true
            }

New cluster:

          "filter" : [
            "trim",
            "lowercase",
            "hpo_autophrase_synonyms",
            "hpo_entity_extraction_synonyms",
            "keep_synonyms"
          ],
          "tokenizer" : "standard"
        }
            "hpo_terms" : {
          "type" : "text",
          "term_vector" : "with_positions_offsets",
          "eager_global_ordinals" : true,
          "analyzer" : "hpo",
          "fielddata" : true
        }

The old cluster, with the same synonym bundle/plugin as the new, will have terms like "HP_0000001", and then new will have "hp_0000001". I can't seem to find any difference between the settings or mappings.

Any thoughts? Is there some global setting somewhere to force field values to be uppercase?