Coolzero1982

Unfreeze firmware via armbian-config.

To my understanding zram is swap substitute. If you re-enable zram then you will have 1giga swap.
Given that you had zram enabled during the first freeze I don't expect that this is a solution.
Does Fhem ram usage increase overtime?

I just used systemctl, after your tests you can enable and start the services again. I also disabled zram not only logging, but you could test by disabling only ram logging. Please note that I did this in order to be able to trace the issue but since i disabled the two services there is no issue
root@cubietruck:~# uptime 20:17:52 up 12 days, 20:20, 1 user, load average: 2.74, 2.77, 2.67 systemctl stop armbian-ramlog.service systemctl disable armbian-ramlog.service systemctl stop armbian-zram-config.service systemctl disable armbian-zram-config.service  
Edit: Well i forgot to say that i did experience 1 issue twice the past 12 days with transmission crashing but I am not sure if this is relevant.  Though I never had issues with transmission on cubietrack using armbian for the past few years. We probably need to alter the unit file so that the daemon restarts after crashing. Here is the log:
Oct 25 20:43:39 cubietruck systemd[1]: transmission-daemon.service: Main process exited, code=killed, status=7/BUS Oct 25 20:43:39 cubietruck systemd[1]: transmission-daemon.service: Failed with result 'signal'.  

In case you want to change this, you are more than welcome to help out:
https://github.com/armbian/config

General instructions are in this doc:
https://www.armbian.com/get-involved

Luxury of uninstall is not implemented. This is Linux, not Android or Windows. Use apt to remove.