Redirecting to prerender.mydomain.com

[viperfx]

I am having an issue where NGINX redirect to my prerendering server rather than serving the HTML from the same domain.

This is roughly what happens, I go to a valid URL and add escaped_fragment to test the pre-rendering

https://domain.com/to-prerender?_escaped_fragment_

It gets redirected to the following URL in the browser

https://prerender.mydomain.com/https://domain.com/to-prerender?_escaped_fragment_

Any idea why this is happening?

I am using a NGINX proxy pass

[viperfx]

This is how my NGINX config looks like

server {
    set $root /usr/share/nginx/html;

    resolver 8.8.8.8;
    set $prerender "prerender.mydomain.com";

    listen 80;
    server_name *.mydomain.com; # all subdomains

    location / {
        root $root;
        try_files $uri @prerender;
    }

    location @prerender{
        proxy_set_header X-Prerender-Token tMHIFXOFsxeqmbExUXo0;
        proxy_set_header Accept-Encoding "gzip";
        gunzip on;

        root $root;

        # don't let rate limiting or server errors interrupt a request
        proxy_intercept_errors on;
        error_page 429 500 502 503 504 =200 /index.html;


        set $prerender 0;

        if ($uri ~ "^(([^.]|\.html?)+)$") {
            set $prerender 0;
        }

        if ($http_user_agent ~* "googlebot|yahoo|bingbot|baiduspider|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot|vkShare|W3C_Validator|redditbot|Applebot|WhatsApp|flipboard|tumblr|bitlybot") {
            set $prerender 1;
        }

        # don't prerender if the prerender user agent is retrieving the page
        if ($http_user_agent ~ "Prerender") {
            set $prerender 0;
        }

        if ($args ~ "_escaped_fragment_") {
            set $prerender 1;
        }

        if ($prerender = 1) {
            rewrite .* /https://$host$request_uri? break;
            proxy_pass http://$prerender$uri;
            break;
        }

        rewrite .* /index.html break;
    }
}