Running docker image of deCONZ on Raspi4 with RaspBee failed

I am trying to update my already running Docker instance of deCONZ on a Raspi4 with RaspBee. I have installed a new SD card from scratch. I followed the instructions at [RaspBee Installation](https://RaspBee documentation) and [GitHub - deconz-community/deconz-docker](https://deCONZ docker readme).

My docker-compose.yml looks like this:

version: '3.6'
services:
  deconz:
    image: deconzcommunity/deconz
    container_name: deconz
    network_mode: host
    restart: always
    privileged: true # This is important! Without it, the deCONZ image won't be able to connect to Raspbee!
    ports:
      - 80:80
      - 443:443
    volumes:
      - /opt/deconz:/opt/deCONZ
      - /etc/localtime:/etc/localtime:ro
    devices:
      - /dev/ttyAMA0
    environment:
      - DECONZ_WEB_PORT=80
      - DECONZ_WS_PORT=443
      - DEBUG_INFO=2
      - DEBUG_ERROR=2
      - DEBUG_APS=2
      - DEBUG_ZCL=0
      - DEBUG_ZDP=0
      - DEBUG_OTAU=0
      - TZ=Germany/Berlin
      - DECONZ_VNC_MODE=0
      - DECONZ_DEVICE=/dev/ttyAMA0

But according to the repeated logging, the connection to the RaspBee via /dev/ttyAMA0 seems to fail:

09:01:25:926 failed open com status: (-3), path: /dev/ttyAMA0
09:01:26:901 wait reconnect 5 seconds
09:01:26:963 COM: /dev/ttyAMA0 :  :  (0x0000/0x0000)
09:01:26:963 dev /dev/ttyAMA0
09:01:26:963 COM: /dev/ttyAMA0 / serialno: , RaspBee
09:01:27:901 wait reconnect 4 seconds
09:01:28:901 wait reconnect 3 seconds
09:01:29:900 wait reconnect 2 seconds
09:01:30:901 wait reconnect 1 seconds
09:01:30:926 COM: /dev/ttyAMA0 :  :  (0x0000/0x0000)
09:01:30:926 dev /dev/ttyAMA0
09:01:30:926 COM: /dev/ttyAMA0 / serialno: , RaspBee
09:01:30:926 failed open com status: (-3), path: /dev/ttyAMA0

On the same hardware, deCONZ runs without any problems when I put the old SD card back in. The docker-compose.yml file differs there of course because of the old version (e.g. image marthoc/deconz).