Cache AJAX GET Requests in Varnish

default.vcl

sub vcl_recv {
# Possibility to cache admin-ajax GET requests
  if ((req.url ~ "admin-ajax.php") && !req.http.cookie ~ "wordpress_logged_in" ) {
      return (hash);
  }
  
#set the length of time to cache ajax GET requests
if ((bereq.url ~ "admin-ajax.php") && !bereq.http.cookie ~ "wordpress_logged_in" ) {
    unset beresp.http.set-cookie;
    set beresp.ttl = 1d;
    set beresp.grace = 1d;
  }

https://guides.wp-bullet.com/how-to-cache-ajax-get-requests-with-varnish-4/