Auth0 + Next.js: How can useUser() lookup user without reading cookies?

Auth0’s useUser() attempts to fetch a logged in user from /api/auth/me, which calls handleAuth(), which initiates Auth0 (creates sessionCache instance, etc.) and calls profileHandler(req, res).

In the profileHandler, we see a call to sessionCache.isAuthenticated(req, res), which in turn checks the sessionCache instance for a previous session entry (key: req object, value: Encrypted object containing user info, access_token, id_token, etc.).

Since each API call, i.e. each call of handleAuth(), whether from /api/auth/me, /api/auth/login, or otherwise, is a separate serverless function call, will profileHandler (/api/auth/me) really ever find an entry in the sessionCache?

I know we add an entry there at login (in callbackHandler), but I do not understand how that cache value persists between two separate Serverless Function calls.

nextjs-auth0 states in the docs:

By default, the session is stateless and stored in an encrypted
cookie. But if you want a stateful session you can provide a store
with get, set and destroy methods to store the session on the

So, we know it is stateless.