start of argononed.service hangs

[plix1014]

I have a Pi4 with booksworm.
I installed the fan controll script with "curl https://download.argon40.com/argon1.sh | bash"
The script hangs when starting the service.
If I manually start the service with "systemctl start argononed.service" systemctl hangs and never gives back the console.
If I directly start the python script "/usr/bin/python3 /etc/argon/argononed.py" it does not daemonize. However, I could manually start the script in background.
I also installed the scripts from this repository with an updated service file. I still get the same issue.
What's wrong?

If I run the systemctl command and in an other terminal I run a "pstree <systemctl pid" I get "systemctl───systemd-tty-ask"

An strace just shows "ppoll([{fd=4, events=POLLIN}, {fd=5, events=POLLIN}], 2, NULL, NULL, 8 <unfinished ...>"