CPU Spikes every few seconds in InternalEditorUtility.get_isApplicationActive()

Using the new Input System v1.8 (though happens in 1.4 as well) every few seconds I get a 5ms CPU spike from the InternalEditorUtility.get_isApplicationActive() method that the Input System calls.

What is causing this?

Sometimes it can be a spike every few seconds or can be 2 or 3 spikes close together all in the same method, it is causing the game cameras to judder nastily. Grabs show the Profiler in the spike and in a normal frame.

This is in Unity-2021-3-LTS.18f1