Nginx – How to Proxy Pass to Docker Container with SSL

I want to serve multiple sites on my server. Each site I suppose to wrap as docker-compose build, each has its own nginx, that listen to one single port

I have a site with hostname site1.com. It's docker compose exposes port 81:

...
services:
  web:
    image: nginx
    ...
    ports:
      - '81:443'
    ...
...

And the client nginx (inside container) listens to everything on 443 and has all ssl settings

server {
        listen 443 ssl;

        ssl_certificate /etc/letsencrypt/fullchain1.pem;
        ssl_certificate_key /etc/letsencrypt/privkey1.pem;
    
        # ...
        # and everything else
}

And here is host nginx, that is just passing from port 80 to 81 according to server_name:

server {
        listen 80;
        listen [::]:80;

        server_name site1.com;

        location / {
                proxy_pass https://localhost:81;
        }
}

For now it's working. But it is insecure. So I try to add 443 forwarding.

server {
        listen 443;
        listen [::]:443;
        server_name bederdinov.me;

        location / {
                proxy_pass https://localhost:81;
        }
}

Nginx restart well, but when I go to https://site1.com I'm getting a ERR_SSL_PROTOCOL_ERROR

It seems quite obvious – host nginx is trying to serve request with ssl, but only docker client nginx knows how to do it

How can I tell host nginx, that it don't have to do anything but only pass all the work to client nginx? Or maybe there is another server software I can use for this task?