Thanks for pointing this out Geoff. I did some more digging and it looks like the default behavior of search is to ignore case and only work with lowercase letters in the search query. If you need case sensitivity, it looks like using the .exact
keyword will enable that.
For example, if I need to find all identities with a display name that starts with Aa
(ex. Aaron) then the following queries will honor the case sensitivity.
attributes.displayName.exact:/Aa.*/
attributes.displayName.exact:Aa*