Essentially, I'd like to have pictrs delete all of the images that aren't uploaded by my users, because my storage usage was going through the roof, so I just disabled the proxying of images. Here is my config:

x-logging: &default-logging
  driver: "json-file"
  options:
    max-size: "50m"
    max-file: "4"

services:
  proxy:
    image: docker.io/library/nginx
    volumes:
      - ./nginx_internal.conf:/etc/nginx/nginx.conf:ro,Z
      - ./proxy_params:/etc/nginx/proxy_params:ro,Z
    restart: always
    logging: *default-logging
    depends_on:
      - pictrs
      - lemmy-ui
    labels:
      - traefik.enable=true
      - traefik.http.routers.http-lemmy.entryPoints=http
      - traefik.http.routers.http-lemmy.rule=Host(`gregtech.eu`)
      - traefik.http.middlewares.https_redirect.redirectscheme.scheme=https
      - traefik.http.middlewares.https_redirect.redirectscheme.permanent=true
      - traefik.http.routers.http-lemmy.middlewares=https_redirect
      - traefik.http.routers.https-lemmy.entryPoints=https
      - traefik.http.routers.https-lemmy.rule=Host(`gregtech.eu`)
      - traefik.http.routers.https-lemmy.service=lemmy
      - traefik.http.routers.https-lemmy.tls=true
      - traefik.http.services.lemmy.loadbalancer.server.port=8536
      - traefik.http.routers.https-lemmy.tls.certResolver=le-ssl


  lemmy:
    image: dessalines/lemmy:0.19.8
    hostname: lemmy
    restart: always
    logging: *default-logging
    volumes:
      - ./lemmy.hjson:/config/config.hjson:Z
    depends_on:
      - postgres
      - pictrs
    networks:
      - default
      - database

  lemmy-ui:
    image: ghcr.io/xyphyn/photon:latest
    restart: always
    logging: *default-logging
    environment:
      - PUBLIC_INSTANCE_URL=gregtech.eu
      - PUBLIC_MIGRATE_COOKIE=true
#      - PUBLIC_SSR_ENABLED=true
      - PUBLIC_DEFAULT_FEED=All
      - PUBLIC_DEFAULT_FEED_SORT=Hot
      - PUBLIC_DEFAULT_COMMENT_SORT=Top
      - PUBLIC_LOCK_TO_INSTANCE=false



  pictrs:
    image: docker.io/asonix/pictrs:0.5
    # this needs to match the pictrs url in lemmy.hjson
    hostname: pictrs
    # we can set options to pictrs like this, here we set max. image size and forced format for conversion
    # entrypoint: /sbin/tini -- /usr/local/bin/pict-rs -p /mnt -m 4 --image-format webp
    #entrypoint: /sbin/tini -- /usr/local/bin/pict-rs run  --max-file-count 10  --media-max-file-size 500 --media-retention-proxy 10d --media-retention-variants 10d  filesystem sled -p /mnt
    user: 991:991
    environment:
      - PICTRS__STORE__TYPE=object_storage
      - PICTRS__STORE__ENDPOINT=https://s3.eu-central-003.backblazeb2.com/
      - PICTRS__STORE__BUCKET_NAME=gregtech-lemmy
      - PICTRS__STORE__REGION=eu-central
      - PICTRS__STORE__USE_PATH_STYLE=false
      - PICTRS__STORE__ACCESS_KEY=redacted
      - PICTRS__STORE__SECRET_KEY=redacted
      - PICTRS__MEDIA__RETENTION__VARIANTS=0d
      - PICTRS__MEDIA__RETENTION__PROXY=0d
      - PICTRS__SERVER__API_KEY=redacted_api_key
      #- PICTRS__MEDIA__IMAGE__FORMAT=webp
      #- PICTRS__MEDIA__IMAGE__QUALITY__WEBP=50
      #- PICTRS__MEDIA__ANIMATION__QUALITY=50
    volumes:
      - ./volumes/pictrs:/mnt:Z
    restart: always
    logging: *default-logging

  postgres:
    image: docker.io/postgres:16-alpine
    hostname: postgres
    volumes:
      - ./volumes/postgres:/var/lib/postgresql/data:Z
      #- ./customPostgresql.conf:/etc/postgresql.conf:Z
    restart: always
    #command: postgres -c config_file=/etc/postgresql.conf
    shm_size: 256M
    logging: *default-logging
    environment:
      - POSTGRES_PASSWORD=password
      - POSTGRES_USER=lemmy
      - POSTGRES_DB=lemmy
    networks:
      - database
  postfix:
    image: docker.io/mwader/postfix-relay
    restart: "always"
    logging: *default-logging

networks:
  default:
    name: traefik_access
    external: true
  database: