I'm not native English speaker and new for the Codewars. I just saw now that "ignore letter case" is correct for ignoring upper case letters. It's a synonim indeed. Sorry for my confusion. Would be better remove the comment. I put ISSUE because didn't find a label like "suggestion". Thanks guys for alerting me.

"case (in)sensitivity" is a pretty standard term, I'd get used to it

Not a kata issue, a suggestion at best.

I don't think this is an issue, "ignore letter case" means the same as "case insensitive", I don't see how this is an improvement.

Would be something like "ignore case sensitivity" instead of "ignore letter case"