Elasticsearch ILIKE does not work even with a correct mapping

Even if we set a lowercase analyzer on a field, searching with an upper case term does not match documents.

The lowercase analyzer works when indexing, the index is done on lowercase.

But when querying using a term filter there is no analyzer applied to the input as state in the documentation:
"term filter: Filters documents that have fields that contain a term (not analyzed)."

It behave the same with regex search or phrase prefix.

So to make it work in addition to the mapping, the input must be transform to lowercase.