Worker as upstream always returns 403

I have one Nginx in my AWS deployment and I want that one location use Cloudflare Worker as the upstream. All requests are returning 403 from Cloudflare although the worker doesn’t return a 403 in code.

Something is blocking my requests but I cannot figure out how to fix it.

My Nginx config:

upstream internal-cloudflare-worker {

server {
        location /get-worker/ {
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto https;
                proxy_ssl_name $host;
                proxy_ssl_server_name on;
                proxy_pass https://internal-cloudflare-worker/;

Question: what could be the reason all my requests are forbidden?