ES + Grafana templating query result always lowercase

I am using Grafana templating feature with ES as datasource. In templating setting, I defined below query

I can get the query result as expected. however, all char in query result is lowercase. such as from Kibana, I can search one entry with value “Aa_Bb”. But within templating, the query result will be aa_bb. Is there any configuration or setting to control query search result?

Not sure, if ES response is lower case, must be an ES option or query option

fixed by updated the query into