@AvdN I do also see the node (from the north of Braunschweig) and two other ones with almost the same DevEUI (4C and 4D at the end). I just installed a Gateway using a self-hosted ChirpStack. My guess is the local energy supplier, who also started to install some gateways and nodes. Also this Thread hints to some energy meters, that use this AppEUI.
I just registered, so cannot send PMs. Maybe you can, so we can solve this privately. Since it’s a regional issue, it’s maybe not of interest for the others.