Error connecting to MariaDB in NextCloud

version: '3' 

services:
  proxy:
    image: jwilder/nginx-proxy:alpine
    labels:
      - "com.github.jrcs.letsencrypt_nginx_proxy_companion.nginx_proxy=true"
    container_name: nextcloud-proxy
    networks:
      - nextcloud_network
    ports:
      - 88:80
      - 444:443
    volumes:
      - ./proxy/conf.d:/etc/nginx/conf.d:rw
      - ./proxy/vhost.d:/etc/nginx/vhost.d:rw
      - ./proxy/html:/usr/share/nginx/html:rw
      - ./proxy/certs:/etc/nginx/certs:ro
      - /etc/localtime:/etc/localtime:ro
      - /var/run/docker.sock:/tmp/docker.sock:ro
    restart: unless-stopped
  
  letsencrypt:
    image: jrcs/letsencrypt-nginx-proxy-companion
    container_name: nextcloud-letsencrypt
    depends_on:
      - proxy
    cap_add:
      - NET_ADMIN
    networks:
      - nextcloud_network
    environment:
      - PUID=998 #change PUID if needed
      - PGID=100  #change PGID if needed
      - TZ=Europe/Warsaw # change Time Zone if needed
      - URL=xxx.duckdns.org
      - SUBDOMAINS=www,
      - VALIDATION=http
      - EMAIL=mail@gmail.com # define email; required to renew certificate
    volumes:
      - ./proxy/certs:/etc/nginx/certs:rw
      - ./proxy/vhost.d:/etc/nginx/vhost.d:rw
      - ./proxy/html:/usr/share/nginx/html:rw
      - /etc/localtime:/etc/localtime:ro
      - /var/run/docker.sock:/var/run/docker.sock:ro
    restart: unless-stopped

  db:
    image: mariadb
    container_name: nextcloud-mariadb
    command: --transaction-isolation=READ-COMMITTED --binlog-format=ROW --innodb-file-per-table=1 --innodb-read-only-compressed=OFF
    networks:
      - nextcloud_network
    volumes:
      - db:/var/lib/mysql
      - /etc/localtime:/etc/localtime:ro
    environment:
      - MYSQL_ROOT_PASSWORD=passw0rd
      - MYSQL_DATABASE=nextcloud
    restart: unless-stopped
  
  app:
    image: nextcloud:latest
    container_name: nextcloud-app
    networks:
      - nextcloud_network
    depends_on:
      - letsencrypt
      - proxy
      - db
    volumes:
      - nextcloud:/var/www/html
      - ./app/config:/var/www/html/config
      - ./app/custom_apps:/var/www/html/custom_apps
      - /srv/dev-disk-by-uuid-c861a38f-6e9d-4fcf-acf6-7b18834c2e7a/data/var/www/html/data
      - ./app/themes:/var/www/html/themes
      - /etc/localtime:/etc/localtime:ro
    environment:
      - TZ=Europe/Warsaw
      - VIRTUAL_HOST=xxx.duckdns.org
      - LETSENCRYPT_HOST=xxx.duckdns.org
      - LETSENCRYPT_EMAIL=mail@gmail.com
    restart: unless-stopped

volumes:
  nextcloud:
  db:

networks:
  nextcloud_network: