The closely spaced triangles definitely look like vice jaw grip marks, the smearing of the marks on the right side makes it look like the piece shifted a bit, not unusual when trying to grip non-square items and work on them with any pressure.
The only marks I’ve seen in my long history of looking at metal that are similar to the little wave marks are from electric grinders, if the tool has a threaded shaft for attaching the abrasive discs, and the threads protrude from the nut affixing the disc (which they usually do), then if the worker touches the work piece with the shaft of the tool (which they occasionally do) it will skip along the surface and leave impressions of the first couple threads in a regular pattern like that.
