That’s exactly the type of thing you’d see with a slipping pulley. What happens is the motor pulley will slip one direction and then jam into place, you get great cuts for a bit. Then at some point it breaks free and rotates to a new position and jams the other direction causing all the next cuts to be off. Have you taken the pulleys off and reset the grub screws? That’s where I would start.
Next I would check your belts, I had one that stretched. Looked fine, but every now and then it would hit that spot and skip a few teeth and caused the same problem as your showing. Retightening doesn’t help because the problem is the teeth on the belt are bad or damaged.
There are definitely other things it could be, bad motor or connection, bad v-wheel or over tightened causing the axis to stick occasionally and miss steps.
But I would start with pulling your motor pulleys off, reset the grub screws (or even better change out as I describe in the post), and check your belts.