Updating docker instance via docker compose fails

Hi! 👋

I'm having a problem with docker instance of SiYuan. I'm hosting on my RPi4 with Ubuntu 22.04.5 LTS using docker compose.

I decided to upgrade my SiYuan 3.1.7 to the latest image. I used docker compose down, then removed the container and image, then used docker compose up -d. It pulled images, built the container alright, but when it starts, the following message is looped and it restarts constantly:

Attaching to main-1
main-1  | Creating group siyuan (1000)
main-1  | addgroup: permission denied (are you root?)
main-1 exited with code 0
main-1  | Creating group siyuan (1000)
main-1  | addgroup: permission denied (are you root?)
main-1  | Creating group siyuan (1000)
main-1  | addgroup: permission denied (are you root?)
main-1  | Creating group siyuan (1000)
main-1  | addgroup: permission denied (are you root?)
main-1  | Creating group siyuan (1000)
main-1  | addgroup: permission denied (are you root?)

I used suggestions on How do I properly update SiYuan on Docker? and Setting up siyuan with docker and exposing it with cloudflare to make it run. The docker-compose.yml file is mostly default and looks like this:

version: "3.9"
services:
  main:
    image: b3log/siyuan
    command: ['--workspace=/siyuan/workspace/', '--accessAuthCode=notMyRealAccesCode']
    user: '1000:1000'
    ports:
      - 6806:6806
      - 6808:6808
    volumes:
      - /siyuan/workspace:/siyuan/workspace
    restart: unless-stopped
    environment:
      - TZ=CET

The workspace folder is owned by the user with UID 1000 and group 1000

> ls -la /
drwxr-xr-x   3 ubuntu ubuntu  4096 Sep 24 07:40 siyuan
> cd siyuan
> ls -la
drwxr-xr-x  6 ubuntu ubuntu 4096 Nov  6 10:50 workspace
> cd workspace
> ls -la
drwxr-xr-x   6 ubuntu ubuntu  4096 Nov  6 10:50 .
drwxr-xr-x   3 ubuntu ubuntu  4096 Sep 24 07:40 ..
drwxr-xr-x   3 ubuntu ubuntu  4096 Nov  6 10:30 conf
drwxr-xr-x  17 ubuntu ubuntu  4096 Sep 24 09:19 data
drwxr-xr-x 651 ubuntu ubuntu 36864 Nov  6 10:30 history
drwxr-xr-x   2 ubuntu ubuntu  4096 Nov  6 10:50 temp

And cat /etc/passwd reveals that ubuntu user is indeed number 1000

ubuntu:x:1000:1000:Ubuntu:/home/ubuntu:/bin/bash

I am at a loss and have no idea how to proceed. Can anyone help me out?

Thanks in advance.