I bought a six socket power extension yesterday to accomodate my growing collection of computers.
I noticed after powering off and disconnecting mains power that the red and green LEDs on the Pi and the blue LED on the Pimoroni shim pulsed briefly with an interval of around 45 seconds. This behaviour continued for some time.
The power strip has two built-in USB charging ports which seem to be responsible for this.
Has anyone else noticed this and - the reason for the post - is it likely to be doing any harm to the Pi in the long run especially when the power strip is fully powered.