Good morning Tom,
as the issue you show on the workpiece looks like Z positioning faults and since you say you got the machine for a while, I would suspect the curly Z cable to be failing randomly because of an internal cable break. Such errors were already reported. Despite being a spiral cable, the Onefinity stock Z stepper cable is NOT a cable made for permanent motion, and if you ask me, I will EXPECT it to fail one day (and the result should look like your workpiece then. See plunge Z issue). Cables for drag chains, like IGUS chainflex® or LAPP ÖLFLEX® are explicitly made for permanent 24/7 motion in the industry for the use in drag chains.
When you attempt to replace the curly Z stepper cable, remember that an open-loop stepper cable has five conductors and not four like the stock cable, as you would take a 4+PE cable. And for a stepper cable, I would always take a shielded one.
Also please have a look at retrofitting strain relief.
I repeat from my other posting above, I would NEVER take the Original Onefinity machine in its stock state into service, with its stock cable management.