Yes all links which you create with SImple URL Shortener is case sensitive by default.

This means that a link with the exactly the same name but where first link uses uppercase characters and the second link uses lower characters will by the system be seen as two different links and treated as such.

Example:
https://shorturl.gg/MyLink

https://shorturl.gg/mylink

In both cases they would be processed as two different links even though the name is almost the same spelling. However you could edit the link target address so both links points to the same destination.