How to regex from nginx variable with map directive

ssl_client_cert_if.conf

##
# I wanted to use same ssl client certificate CA in nginx for multple client certs
# but restrict the users outside our organisation accessing everything.
# Because I can decide what to put into the emailAddress I can force verify everything and only pass the proper users.
##

##
# This way you can restrict users only with email addresses from @koodimonni.fi
# Put this into http context in nginx configs
##

map $ssl_client_s_dn $koodimonni_user {
  default "false";
  ~emailAddress=.*@koodimonni.fi "true";
}

##
# Use the result in if
##
if ($koodimonni_user = "true") {
  proxy_pass some_super_secure_server;
}

stop_flood_nginx.conf

map $request_uri $isAttack {
    default "false";
    ~*\?[0-9] "true";
    ~*\?\= "true";
    ~*\?busqueda "false";
    ~*\?_ "false";
    ~*\?utm "false";
    ~*\?fbclid "false";
    ~*\? "true";
}

server {
  listen 80;
  server_name site.me;
  location / {
     if ($isAttack = "true") {
     add_header Content-Type text/html;
     return 200 ":/";
     ...
     proxy_set_header X-Real-IP $remote_addr;
     proxy_set_header X-Forwarder-For $proxy_add_x_forwarded_for;
     proxy_set_header Host $http_host;
     proxy_set_header X-NginX-Proxy true;
     proxy_pass http://my_app;
     proxy_redirect off;
  }
}