Same issue here. I could trace it down to any app that would take a large amount of RAM, not only Fennec: NewPipe, AntennaPod, OsmAnd~… The same FP2 runs well with Fairphone OS 19.11. There is definitely something about Lineage OS that makes a difference:
- does it take more RAM overall?
- could the daemon-that-kill-processes-that-take-too-much-RAM kill the process of a system app, leading to the reboot?
- is it just the system lagging, and when this happens, Lineage OS reboots because it thinks it is stuck?
I have tried collecting data about it, but it produced such a large directory that I don’t know where to start the investigation from.
I would like to go back to Fairphone OS because of this, but that would be no less frustrating given the number of apps I use that do not support Android 7. I cannot wait for Fairphone OS with Android 9…