So far, the system has been worry-free for 6 days, which is promising. I’ve updated Core two times during this time. Backup size is 620 MB and increasing, which I’ve been told is not a good sign. Let’s give it a month and see if it’s fixed or not. Thank you for the detailed post, I will check your suggestions and questions more thoroughly if problems come back.
It’s gonna keep increasing for at least 1 more day, given you have purge_keep_days: 7 & it’s only been 6 days.
A month without any issues - looks like either power supply or USB-SSD adapter was the culprit. I’ll let you know if something similar happens again!
Backup size did stop increasing eventually as suggested above 