Bad bearing on a moving part. Or a bur along a rail, It catches just enough to cause the smooth motion to jitter a bit as the head moves along. Blobbing the material down instead of spreading it nice and even.

You have a draft going through your room, I used to have same issue when my printer was beside a window. Less when I moved the printer to middle of the room and issue was gone when put the printer into a closet. With closed doors.

You can try lowering bed temperature to, the warm bed keeps lower layer pliable but the upper layers cool and contract pulling the more flexible layer up and away. So a cooler bed temp should make the bottom layers more ridgid.

Everyone worried about the bending force, the retaining slots will tear out and drop the damn thing on the desk well before it bends.

Ig you think that’s bad wait until you get multiple retractions going that the rocking motion of the 3kg Is probably going to be enough to pull the filament right out of the extruder.