Nginx overwrites desired port when using proxy_pass on a subdirectory to direct request to node server

I have the following nginx config:

server {
    listen 80;
    listen 443 ssl;
    
    ssl on;
        ssl_certificate /home/tom/local.tjrhodes.com.pem; 
    ssl_certificate_key /home/tom/local.tjrhodes.com-key.pem;

    root /home/tom/Nextcloud/local.tjrhodes.com/webroot/;
    
    error_log /home/tom/Nextcloud/local.tjrhodes.com/logs/error.log;

    # Add index.php to the list if you are using PHP
    index index.html index.htm index.nginx-debian.html;

    server_name local.tjrhodes.com;

    location / {
        # First attempt to serve request as file, then
        # as directory, then fall back to displaying a 404.
        try_files $uri $uri/ =404;
    }
    
    location /pat/ {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Host $host;
            proxy_set_header Host $host;
            proxy_pass http://127.0.0.1:3000;
            proxy_redirect off;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
    }

}

I call the /pat/ path with fetch on the client but the port 3000 on the proxy_pass command is overwritten with 443 as I’m testing locally over https. What am I missing in the config?
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I’ve tried the node server calling it directly with the correct port (127.0.0.1:3000) and it responds ok. I can’t make the request from the client when connecting over https though.