Dear awesome people of this thread,
As mentioned before, I replaced the cable, swapped to different guitars (with/out single coils), tried disconnecting devices like USBs and chargers, paid an electrician to check my apartment grounding line.
After reading your comments and talking with an e.engineer from work, I did the following:
I started by disconnecting devices such as USBs, including the one connected to the Kemper.
Ending up only with my Kemper, PC, and monitors connected, I decided to try another socket, just in case it's not a grounding issue of some sort, and changed the extension cord I have to another one.
I started moving around my guitar in weird angles and noticed some changes in the noises. Touching the pickups/bridge/strings stopped the noises too. So clearly I'm ~picking up~ noises from somewhere. I placed the guitar on my chair so nothing touches it while hearing the "beep"ing. The more I rolled the chair away from the desk, the less I heard noises (the other side of the room had NO NOISES!), the more I got close to my desk the stronger the noises. Then testing the last thing @RosboneMako said - on the right side of my desk, right behind the fake closet - which is actually a niche for the kitchen fridge. I placed the chair with the guitar facing it, and the noises were the worst. I disconnected the fridge and voila - no noises!!! after some research, seems like it's common with inverter fridges.
Just so I am extra sure this is the guitar and not maybe the cable, I rolled the cable and moved it back and forward from the "closet", there was no change, so I know for sure it's not a cable placement issue.
Now that I know it's the fridge, any idea what I can do about it?