Deployed fresh new and ran nginx -T in the container:

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
# configuration file /etc/nginx/nginx.conf:
user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;
error_log stderr notice;

events {
        worker_connections 768;
        # multi_accept on;
}

http {
        client_max_body_size 100M;
        rewrite_log on;

        log_format devlogging '$remote_addr - $remote_user [$time_local] "proxy_host" $proxy_host "proxy_add_x_forwarded_for" $proxy_add_x_forwarded_for "upstream_addr" $upstream_addr "proxy_protocol_addr" $proxy_protocol_addr "proxy_protocol_server_addr" $proxy_protocol_server_addr "request_uri" $request_uri "request" $request "http_x_forwarded_for" $http_x_forwarded_for "status" $status "args" $args';

        ##
        # Basic Settings
        ##

        sendfile on;
        tcp_nopush on;
        types_hash_max_size 2048;
        # server_tokens off;

        # server_names_hash_bucket_size 64;
        # server_name_in_redirect off;

        include /etc/nginx/mime.types;
        default_type application/octet-stream;

        ##
        # SSL Settings
        ##

        ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3; # Dropping SSLv3, ref: POODLE
        ssl_prefer_server_ciphers on;

        ##
        # Logging Settings
        ##

        access_log /dev/stdout devlogging;

        ##
        # Gzip Settings
        ##

        gzip on;

        # gzip_vary on;
        # gzip_proxied any;
        # gzip_comp_level 6;
        # gzip_buffers 16 8k;
        # gzip_http_version 1.1;
        # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

        ##
        # Virtual Host Configs
        ##

        include /etc/nginx/conf.d/*.conf;
        include /etc/nginx/sites-enabled/*;
}

# configuration file /etc/nginx/mime.types:

types {
    text/html                             html htm shtml;
    text/css                              css;
    text/xml                              xml;
    image/gif                             gif;
    image/jpeg                            jpeg jpg;
    application/javascript                js;
    application/atom+xml                  atom;
    application/rss+xml                   rss;

    text/mathml                           mml;
    text/plain                            txt;
    text/vnd.sun.j2me.app-descriptor      jad;
    text/vnd.wap.wml                      wml;
    text/x-component                      htc;

    image/avif                            avif;
    image/png                             png;
    image/svg+xml                         svg svgz;
    image/tiff                            tif tiff;
    image/vnd.wap.wbmp                    wbmp;
    image/webp                            webp;
    image/x-icon                          ico;
    image/x-jng                           jng;
    image/x-ms-bmp                        bmp;

    font/woff                             woff;
    font/woff2                            woff2;

    application/java-archive              jar war ear;
    application/json                      json;
    application/mac-binhex40              hqx;
    application/msword                    doc;
    application/pdf                       pdf;
    application/postscript                ps eps ai;
    application/rtf                       rtf;
    application/vnd.apple.mpegurl         m3u8;
    application/vnd.google-earth.kml+xml  kml;
    application/vnd.google-earth.kmz      kmz;
    application/vnd.ms-excel              xls;
    application/vnd.ms-fontobject         eot;
    application/vnd.ms-powerpoint         ppt;
    application/vnd.oasis.opendocument.graphics        odg;
    application/vnd.oasis.opendocument.presentation    odp;
    application/vnd.oasis.opendocument.spreadsheet     ods;
    application/vnd.oasis.opendocument.text            odt;
    application/vnd.openxmlformats-officedocument.presentationml.presentation    pptx;
    application/vnd.openxmlformats-officedocument.spreadsheetml.sheet    xlsx;
    application/vnd.openxmlformats-officedocument.wordprocessingml.document    docx;
    application/vnd.wap.wmlc              wmlc;
    application/wasm                      wasm;
    application/x-7z-compressed           7z;
    application/x-cocoa                   cco;
    application/x-java-archive-diff       jardiff;
    application/x-java-jnlp-file          jnlp;
    application/x-makeself                run;
    application/x-perl                    pl pm;
    application/x-pilot                   prc pdb;
    application/x-rar-compressed          rar;
    application/x-redhat-package-manager  rpm;
    application/x-sea                     sea;
    application/x-shockwave-flash         swf;
    application/x-stuffit                 sit;
    application/x-tcl                     tcl tk;
    application/x-x509-ca-cert            der pem crt;
    application/x-xpinstall               xpi;
    application/xhtml+xml                 xhtml;
    application/xspf+xml                  xspf;
    application/zip                       zip;

    application/octet-stream              bin exe dll;
    application/octet-stream              deb;
    application/octet-stream              dmg;
    application/octet-stream              iso img;
    application/octet-stream              msi msp msm;

    audio/midi                            mid midi kar;
    audio/mpeg                            mp3;
    audio/ogg                             ogg;
    audio/x-m4a                           m4a;
    audio/x-realaudio                     ra;

    video/3gpp                            3gpp 3gp;
    video/mp2t                            ts;
    video/mp4                             mp4;
    video/mpeg                            mpeg mpg;
    video/quicktime                       mov;
    video/webm                            webm;
    video/x-flv                           flv;
    video/x-m4v                           m4v;
    video/x-mng                           mng;
    video/x-ms-asf                        asx asf;
    video/x-ms-wmv                        wmv;
    video/x-msvideo                       avi;
}

# configuration file /etc/nginx/sites-enabled/default:
server {
    listen       80 default_server;
    listen       [::]:80 default_server;
    server_name  _;
    root         /usr/share/nginx/html;
    proxy_http_version 1.1;
    client_max_body_size 100M;
    proxy_buffering off;
    proxy_set_header Connection "";

    # compression
    gzip            on;
    gzip_comp_level 1;
    gzip_http_version 1.0;
    gzip_min_length 512;
    gzip_proxied    expired no-cache no-store private auth;
    gzip_types  text/plain
                text/css
                application/json
                application/javascript
                application/x-javascript
                text/xml application/xml
                application/xml+rss
                text/javascript
                application/x-font-ttf
                font/woff2
                image/svg+xml
                image/x-icon;

    # Load configuration files for the default server block.
    include /etc/nginx/default.d/*.conf;

    location / {
        try_files $uri $uri/ /index.html;
    }

    location /version.json {
        add_header Cache-Control 'no-cache';
    }

    location /api {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $proxy_host;
        proxy_pass 

;
        rewrite /api/(.*) /$1  break;
    }

    location /widgets {
        alias /usr/share/nginx/widgets;
        try_files $uri $uri/ /widgets/index.html;
        add_header Content-Security-Policy "frame-ancestors *";
    }


    error_page 404 /404.html;
        location = /40x.html {
    }

    error_page 500 502 503 504 /50x.html;
        location = /50x.html {
    }
}

(same issue btw)