Well, one thing that doesn't really work nicely with NPM is Snikket.

services:
  app:
    image: 'jc21/nginx-proxy-manager:latest'                        restart: unless-stopped
    ports:                                                            - '325:80'
      - '81:81'                                                       - '326:443'
    volumes:                                                          - ./data:/data                                                  - ./letsencrypt:/etc/letsencrypt

I mean I got them portmapped to other ports so... I dunno

apparently it's my native nginx.... wtf. I used

sudo systemctl stop nginx

And the websites that had the nginx error went down. I don't know how this could even happen? My containers use their own nginxes??? Maybe the mix of native nginx and docker nginx is messing everything up, if I can't find a solution I'm probably gonna nuke my native nginx and use docker nginx for all of my nginx needs

nginx proxy manager's in a docker container reverse proxying my nginx docker containers, and native nginx is reverse proxying snikket container because nginx proxy manager doesn't go well with snikket.

Here's the nginx config for my snikket.

server {                                                          # Accept HTTP connections                                       listen 80;
  listen [::]:80;

  server_name chat.allinuxuser.xyz;
  server_name groups.chat.allinuxuser.xyz;
  server_name share.chat.allinuxuser.xyz;
                                                                  location / {                                                        proxy_pass http://localhost:5080/;                              proxy_set_header      Host              $host;
      proxy_set_header      X-Forwarded-For   $proxy_add_x_forwarded_for;
                                                                      # This is the maximum size of uploaded files in Snikket
      client_max_body_size 104857616; # 100MB + 16 bytes          }
}                                                                                                                               server {                                                          # Accept HTTPS connections
  listen [::]:443 ssl;                                            listen 443 ssl;
  ssl_certificate /etc/letsencrypt/live/allinuxuser.xyz-0001/fullchain.pem;                                                       ssl_certificate_key /etc/letsencrypt/live/allinuxuser.xyz-0001/privkey.pem;
                                                                  server_name chat.allinuxuser.xyz;                               server_name groups.chat.allinuxuser.xyz;
  server_name share.chat.allinuxuser.xyz;                       
  location / {
      proxy_pass https://localhost:5443/;
      proxy_set_header      Host              $host;
      proxy_set_header      X-Forwarded-For   $proxy_add_x_forwarded_for;
      # REMOVE THIS IF YOU CHANGE `localhost` TO ANYTHING ELSE ABOVE
      proxy_ssl_verify      off;
      proxy_set_header      X-Forwarded-Proto https;
      proxy_ssl_server_name on;

      # This is the maximum size of uploaded files in Snikket
      client_max_body_size 104857616; # 100MB + 16 bytes

      # For BOSH and WebSockets
      proxy_set_header Connection $http_connection;
      proxy_set_header Upgrade $http_upgrade;
      proxy_read_timeout 900s;

  }
}

Here's the docker-compose for one of the sites i'm running that's been affected by the weird nginx error.

version: "3"                                                    services:
    client:                                                           image: nginx
      restart: unless-stopped                                         ports:
            - 5973:80                                                 volumes:
            - ./allinuxuser-website:/usr/share/nginx/html

Please tell me if there's any more logs I need to provide.

What kind of logs should I post?

tcp   LISTEN    0      4096                                     0.0.0.0:9443                   0.0.0.0:*     users:(("docker-proxy",pid=1550,fd=4))                                                                                                             tcp   LISTEN    0      511                                      0.0.0.0:443                    0.0.0.0:*     users:(("nginx",pid=2511847,fd=6),("nginx",pid=2511846,fd=6),("nginx",pid=2511845,fd=6),("nginx",pid=2511844,fd=6),("nginx",pid=2511843,fd=6))     tcp   LISTEN    0      511                                      0.0.0.0:5443                   0.0.0.0:*     users:(("nginx",pid=2540528,fd=6),("nginx",pid=2540399,fd=6))                                                                                      tcp   LAST-ACK  0      1                                  192.168.0.107:443               91.84.87.137:40016                                                                                                                                                    tcp   LISTEN    0      4096                                        [::]:9443                      [::]:*     users:(("docker-proxy",pid=1560,fd=4))                                                                                                             tcp   LISTEN    0      511                                         [::]:443                       [::]:*     users:(("nginx",pid=2511847,fd=5),("nginx",pid=2511846,fd=5),("nginx",pid=2511845,fd=5),("nginx",pid=2511844,fd=5),("nginx",pid=2511843,fd=5))     tcp   LISTEN    0      511                                         [::]:5443                      [::]:*     users:(("nginx",pid=2540528,fd=7),("nginx",pid=2540399,fd=7))

I don't know how to even interpret this, I know it says nginx but which nginx?? I got like 4 nginx web servers running

Thanks! Turns out nginx proxy manager was using 443. Changed the port and now nginx throws no errors!