I had this issue today while making my own server, i think i fixed it by telling it to not use the dev version of lemmy and the v1.17.1 version of lemmy-ui.

If you need my whole docker-compose.yml:

version: "3.3"
networks:
  # communication to web and clients
  lemmyexternalproxy:
  # communication between lemmy services
  lemmyinternal:
    driver: bridge
    internal: true

services:
  proxy:
    image: nginx:1-alpine
    networks:
      - lemmyinternal
      - lemmyexternalproxy
    ports:
      # actual and only port facing any connection from outside
      # Note, change the left number if port 1236 is already in use on your system
      # You could use port 80 if you won't use a reverse proxy
      - "82:82"
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro,Z
    restart: always
    depends_on:
      - pictrs
      - lemmy-ui

  lemmy:
    image: dessalines/lemmy:0.17.4
    # use this to build your local lemmy server image for development
    # run docker compose up --build
    #build:
    #  context: ../
    #  dockerfile: docker/Dockerfile
      # args:
      #   RUST_RELEASE_MODE: release
    # this hostname is used in nginx reverse proxy and also for lemmy ui to connect to the backend, do not change
    hostname: lemmy
    networks:
      - lemmyinternal
      - lemmyexternalproxy
    restart: always
    environment:
      - RUST_LOG="warn,lemmy_server=debug,lemmy_api=debug,lemmy_api_common=debug,lemmy_api_crud=debug,lemmy_apub=debug,lemmy_db_schema=debug,lemmy_db_views=debug,lemmy_db_views_actor=debug,lemmy_db_views_moderator=debug,lemmy_routes=debug,lemmy_utils=debug,lemmy_websocket=debug"
      - RUST_BACKTRACE=full
    volumes:
      - ./lemmy.hjson:/config/config.hjson:Z
    depends_on:
      - postgres
      - pictrs

  lemmy-ui:
    image: dessalines/lemmy-ui:0.17.4
    # use this to build your local lemmy ui image for development
    # run docker compose up --build
    # assuming lemmy-ui is cloned besides lemmy directory
    # build:
    #   context: ../../lemmy-ui
    #   dockerfile: dev.dockerfile
    networks:
      - lemmyinternal
    environment:
      # this needs to match the hostname defined in the lemmy service
      - LEMMY_UI_LEMMY_INTERNAL_HOST=lemmy:8536
      # set the outside hostname here
      - LEMMY_UI_LEMMY_EXTERNAL_HOST=localhost:1234
      - LEMMY_HTTPS=true
    depends_on:
      - lemmy
    restart: always

  pictrs:
    image: asonix/pictrs:0.4.0-beta.19
    # 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
    networks:
      - lemmyinternal
    environment:
      - PICTRS_OPENTELEMETRY_URL=http://otel:4137
      - PICTRS__API_KEY=API_KEY
      - RUST_LOG=debug
      - RUST_BACKTRACE=full
      - PICTRS__MEDIA__VIDEO_CODEC=vp9
      - PICTRS__MEDIA__GIF__MAX_WIDTH=256
      - PICTRS__MEDIA__GIF__MAX_HEIGHT=256
      - PICTRS__MEDIA__GIF__MAX_AREA=65536
      - PICTRS__MEDIA__GIF__MAX_FRAME_COUNT=400
    user: 991:991
    volumes:
      - ./volumes/pictrs:/mnt:Z
    restart: always

  postgres:
    image: postgres:15-alpine
    # this needs to match the database host in lemmy.hson
    # Tune your settings via
    # https://pgtune.leopard.in.ua/#/
    # You can use this technique to add them here
    # https://stackoverflow.com/a/30850095/1655478
    hostname: postgres
    command:
      [
        "postgres",
        "-c",
        "session_preload_libraries=auto_explain",
        "-c",
        "auto_explain.log_min_duration=5ms",
        "-c",
        "auto_explain.log_analyze=true",
        "-c",
        "track_activity_query_size=1048576",
      ]
    networks:
      - lemmyinternal
      # adding the external facing network to allow direct db access for devs
      - lemmyexternalproxy
    ports:
      # use a different port so it doesnt conflict with potential postgres db running on the host
      - "5433:5432"
    environment:
      - POSTGRES_USER=lemmy
      - POSTGRES_PASSWORD=InsertDBPasswordHere
      - POSTGRES_DB=lemmy
    volumes:
      - ./volumes/postgres:/var/lib/postgresql/data:Z
    restart: always