Audiofuse 16Rig - Strange Pulse going on with not powered gear

Several devices are connected to the audio inputs on my Audiofuse. When these devices are not turned on or have no power at all, there is a strange, regular pulse going on every few seconds on some inputs.

This is audible in the DAW and disappears as soon as the device is switched on. It is also visible on the gain LED on my Vermona reverb, that lights up every few seconds even though it’s not switched on. It’s visible in the Audiofuse mixer, too.
Happens not with all devices, just two of the seven, that are connected. (Vermona Spring Reverb and Jomox MBase11)

Here you see that audio “thing” happening. This repeats around every five seconds.

Anyone else noticed this, too and understands whats going on here?

Just noticed that this happens only when I turn off the power strip for these two devices, but leave the actual power switches in ON position. When toggle the switches to off, it stops. Still weird.