I agree that it sounds like a software priority issue. But rather than lack of priority I would guess something else having too high priority thus interfering with the keyboard operation, as not everyone reports it. But could still be a system isssue, where some other system stuff gets activated by some actions or apps not all use or use the same way.
Starting with the ones power consumption points at as posssible culprits, I would try to stop (or even deactive/uninstall) stuff and see if whatever triggers the phenomenon can be narrowed down.
Ultimately trying a factory reset, and t