You should write in your Docker compose the following;

  pgadmin:
    image: dpage/pgadmin4
    container_name: pgadmin
    restart: always
    environment:
      PGADMIN_DEFAULT_EMAIL: ${PGADMIN_DEFAULT_EMAIL}
      PGADMIN_DEFAULT_PASSWORD: ${PGADMIN_DEFAULT_PASSWORD}
      PGADMIN_CONFIG_X_FRAME_OPTIONS: '""'
    ports:
      - "5050:80"

If you are using only Docker, you can:

docker run -p 80:80 \
-e '[email protected]' \
-e 'PGADMIN_DEFAULT_PASSWORD=SuperSecret' \
-e 'PGADMIN_CONFIG_X_FRAME_OPTIONS=""' \
-d dpage/pgadmin4