Hi, I'm migrating my codebase from Nextjs14 to NextJS15

I have a server action file containing the following code

'use server' 
export async function setCookie(cookieName: string, content: string) {
    console.log({ cookieName, content })
    return (await cookies()).set(cookieName, content)
}

And this function called inside a Client component like this

    useEffect(() => {
        if (basket && !isEmptyObject(basket)) {
            setCookie('basket', 'lol')
        }
    }, [basket])

It used to work perfectly, but now NextJS 15 is throwing this error :

[ Server ] Error: Only plain objects, and a few built-ins, can be passed to Client Components from Server Components. Classes or null prototypes are not supported.
  {}

See how I explicitly send a "lol" string as a parameter ? What is the reason here ?

Maybe I'm doing things wrong ? My use case it that based on a user interaction in a client component I need to define a cookie

Thank you for your time