I am using Altium as a hobbyst since some years. Until now, I did not have this problem before.
When I making interactive routing between two parts, it makes recently always a small line (marked in the attachmet as "problem") at the endpoint. I think I changed something accidentally (via shortcut or so), because that kind of behaviour was not there before.
What is this option, and how can I switch it off?
It is not clear the question at all, but if it is what it seems, the line that indicates missing connection from devices of the same net is always updated to the nearest primitive among both devices, that is, during interactive routing, the center of the track being routed toward the target device, it get the "missing connection" wire.