I talked with the dev team, and this is a new change in A16 with how background tasks are handled by Android’s task killer.
In prior versions, it mostly was concerned with amount of available RAM/swap space and would kill apps that were least recently used or very resource-intensive.
Now, it is looking mostly at recent CPU-usage for background tasks, and killing those that are more CPU-hungry, regardless of amount of available RAM/swap.
So, this change in behavior should result in better standby battery life, but is apparently a bit aggressive on older SOCs with CPUs that need to work longer/harder, like ours.
I would expect this to get some tuning as time goes on, but at least for now, this is what it is.
Edit:
The team have already adjusted the behavior for 16.2.0 to be more similar to prior Android versions, but it still might behave a bit differently due to changes in the OS and how background tasks are handled.

