Why deleting session record in django server cache doesn't make me logout?

I store session in redis cache

SESSION_ENGINE = "django.contrib.sessions.backends.cache" SESSION_CACHE_ALIAS = "default"

I delete the record from cache, the key is "django.contrib.sessions.backends.cache"+the session key.

But I am still logged in after I reload the page, just got a new session. Why I am not logged out after I remove the session from the cache?