Nextcloud Office insert image from Nextcloud to text document fails

nothing special, likely you can use Collabora CODE for Nextcloud with Docker

# docker compose config collabora
services:
  collabora:
    cap_add:
      - MKNOD
    cpus: 2
    container_name: collabora
    environment:
      VIRTUAL_HOST: collabora.mydomain.tld
      VIRTUAL_PORT: "9980"
      VIRTUAL_PROTO: http
      aliasgroup1: https://nc.mydomain.tld:443
      aliasgroup2: https://dev-nc.techisfun.net:443
      aliasgroup3: https://test-nc.techisfun.net:443
      dictionaries: de_DE en_US es_ES ru
      extra_params: --o:ssl.enable=false --o:ssl.termination=true --o:user_interface.mode=compact --o:remote_font_config.url=https://dev-nc.techisfun.net:443/apps/richdocuments/settings/fonts.json --o:logging.level=warning
      password: ***mysecretpwd***
      username: ***admin user***
    expose:
      - "9980"
    image: collabora/code:25.04.5.2.1
    labels:
      traefik.enable: "true"
      traefik.http.routers.collabora.middlewares: secHeaders5@file
      traefik.http.routers.collabora.rule: Host(`collabora.mydomain.tld`)
      traefik.http.routers.collabora.tls: "true"
      traefik.http.routers.collabora.tls.certresolver: letsencryptresolver
      traefik.http.services.collabora.loadbalancer.server.port: "9980"
    mem_limit: "8589934592"
    networks:
      proxy: null
    restart: unless-stopped
    tty: true
    volumes:
      - type: bind
        source: /etc/timezone
        target: /etc/timezone
        read_only: true
        bind:
          create_host_path: true
      - type: bind
        source: /etc/localtime
        target: /etc/localtime
        read_only: true
        bind:
          create_host_path: true
      - type: bind
        source: /ssd/infra/code_no_welcome
        target: /usr/share/coolwsd/browser/dist/welcome
        read_only: true
        bind:
          create_host_path: true
networks:
  proxy:
    name: proxy
    external: true