Touchpad turns buggy spontaneously

I’m currently using L15v4 for almost three months. During this period I faced the following heisenbug three times (i.e. it is rare enough to ignore it, but I’m just curious at which level the problem could be). I’m not sure whether this is a software or a hardware bug.

When the system runs for a while (few days), there is a small chance that the touchpad stops working normally and instead reacts as if there is a small piece of dirt or dust on it: 50% (roughly) of single-finger touches are simply ignored; in 30% of such touches the touchpad reacts as if these were two-finger touches (acts as a mouse click), and in 20% the mouse pointer moves, but not smoothly - instead, the pointer “waits” for a while and then “jumps” in the correct direction.

Weirdly, though this bug does not go away after hot reboot, it always goes away after cold reboot (no matter how long the machine stays off - even one second is enough).

Is there any kind of resident software (i.e. not running on the main CPU and not being reloaded by the kernel during its startup) or memory (which could persist some buggy state unless unpowered) in the touchpad itself, which could explain the fact that the bug survives hot reboots, but goes away after powering the system down?

OS: original PureOS (one time) and ArchLinux (the rest two times).