Yes, that is what I am referring to.
Web browsers request pages from web servers by using a URL.
The URL is the address of a web page, like: https://www.w3schools.com.
URL encoding converts characters into a format that can be transmitted over the Internet.
URLs can only be sent over the Internet using the ASCII character-set.
Since URLs often contain characters outside the ASCII set, the URL has to be converted into a valid ASCII format.
URL encoding replaces unsafe ASCII characters with a “%” followed by two hexadecimal digits.
URLs cannot contain spaces. URL encoding normally replaces a space with a plus (+) sign or with %20.
This has nothing to do with the Ivory Search plugin.
Please find more information about it on the below page.
https://www.w3schools.com/tags/ref_urlencode.ASP