Strange battery drain on some Go Ultras

[andplan]

We are using several Reolink Go Ultras for construction site documentation (in Austria). They take images every 20 minutes. We have been running them for about 2 years with the neolink "image" argument and "debug" in the toml file to get additional cam info (temperature, battery power). From the 4th to the 5th of November, we noticed a rise in cam temperature together with a marked loss of battery power on 3 of our cams. Others were not affected. After 10 hours, the cams shut down due to low battery, but they had been working normally up to that point. After PV charging, they resumed working normally. During this issue, I performed a system reboot on one cam, but it had no effect. Since neolink is essential for our service, I wanted to ask if anyone else has observed similar behavior and what could be the reason for it. Automatic firmware updates are turned off. Could Reolink still inject updates into the cams? Additional info: No video streams or other accesses occurred besides the 20-minute images on our side.