Keyword Search is Case Sensitive? Giving different result for listings found

[rosegarden]

Keyword search is giving me random result when it comes to listing found

For example, I search the word "blue" in different case all gives different search result

Blue - 444 Listings found
BLue - 369 Listings found
BLUe - 368 Listings found
BLUE - 379 Listings found

blue - 422 Listings found
bluE - 368 Listings found
blUE - 368 Listings found
bLUE - 368 Listings found

I select "Any words" as a keyword search option

Does the field type has a factor to play ?

Name of field : additional_information
type : textarea