How to correctly setup sub-domains with ssl and nginx as a proxy?

I managed to configure nginx reverse proxys and ssl in order to run a Directus 9 Docker installation.

But my actual goal is to run 3 separate Directus 9 Docker installations on 3 subdomains (like “jvds.my-domain.org”). The sub-domains open the proper index sites (from their defined subfolders) as long as there is no proxy_pass defined (in the nginx block configuration):

#/etc/nginx/sites-enabled/jvds.scores-catalog.org.conf

server {
    root /var/www/jvds.scores-catalog.org/html;
    index index.html index.htm index.nginx-debian.html;
    server_name jvds.scores-catalog.org;
    location / {
        try_files $uri $uri/ =404;
        #proxy_pass http://127.0.0.1:8055;

As soon as proxy_pass is active, the subdomain does not open properly; and the running terminal on the main domain (the one with the working Directus installation) detects something and prints to the console.

Also, when running docker-compose, this command seems to influence all instances! A docker-compose down stops all docker instances. How can I execute docker containers in each subdomain separately?