varnish strip backend cookies

backend_response.vcl

sub vcl_backend_response {
    # Happens after we have read the response headers from the backend.
    #
    # Here you clean the response headers, removing silly Set-Cookie 
    # headers and other mistakes your backend does.

    if (bereq.url ~ "^/$" ||
        bereq.url ~ "^/(frauen|maenner|kinder|outlet|marke)(/.+)?" ||
        bereq.url ~ "^/api/(seen2bought/|similarProduct/|product\?)" ||
        bereq.url ~ "\.(css|js)\?.*" ||
        bereq.url ~ "\.(png|gif|jpg|ico|js|css|xml|pdf|woff|ttf)$"
    ){
        # time-to-live 30 minutes
        set beresp.ttl = 1800s;
        unset beresp.http.set-cookie;
        unset beresp.http.Pragma;
        unset beresp.http.Expires;
    }
    
    # dont cache redirects and errors
    if (beresp.status >= 300) {
        set beresp.uncacheable = true;
        set beresp.ttl = 30s;
        return (deliver);
    }
    # …
    return (deliver);
}