Error 429 slow down

You are having Varnish issues. If you don’t have access to Varnish on your web server, or you are wondering “what the heck is Varnish?”, you should contact your webhost.

Else, you can look at this:

https://www.varnish-cache.org/docs/trunk/users-guide/troubleshooting.html#varnish-gives-me-guru-meditation