Having issues clearing cookies in Safari via NextJS

I have a web application built in NextJS that I use cookies to handle persisting authentication details. I clear the cookies on logout and this works in other browsers.

However, when I run this on Safari, it seems the browser is caching the cookie information. When I use the Safari debugger, I do not see the cookies in the Storage view, however, when I use document.cookies, I can retrieve them fine - which should not happen. This is not the case in Chrome.

I can't find any information on this online, so any help or insights would be greatly appreciated.