cookie is not set in the browser when using setCookie from h3 inside a Nuxt server endpoint

[ghost]

Environment

Nuxt (compatibilityVersion 4) v.3.15.2
node >20

Reproduction

Please check the description below

Describe the bug

Hi,
I'm using Nuxt with compatibilityVersion 4.
I have a server api endpoint that gets called from an external website, in the endpoint I receive some data that I put in my mongo database and then I have this setCookie

setCookie(event, 'session_key',${sessionValue}.${signature}`, {
httpOnly: true,
secure: process.env.NODE_ENV === 'production',
path: '/',
maxAge: 60 * 60 * 24 // 1 day
})

console.log('Cookie Set:', event.node.res.getHeader('Set-Cookie'))`

this is the log of my cookie in the server logs
Cookie Set: [ 'session_key=%7B%22senderID%22%3A%22S007%22%2C%22date%22%3A1737716793583%7D.gVks6cjZwsazQFGgcFTq%2F39eOFVFAMJ8I0Sw4tXR5fw%3D; Max-Age=86400; Path=/; HttpOnly; Secure; SameSite=Lax' ]

So it seems that the endpoint is triggered, my data gets inside my mongo db, but the cookie is not set in the browser.
I'm using nuxt-security allowing the first domain to make the POST request to my endpoint and everything seems working ok, I tried to disable nuxt-security but the problem is still there. The cookie is logged but not set in the browser.

Additional context

No response

Logs

[pi0]

thanks. moving to discussion until we have a minimal reproduction.