accuracy failure

It definitely appears to be something mechanical that is loose or slipping and allowing Y-axis travel.

The disconnect where the large letter D separates, is probably the start and the stop of the loop.

The Serif or ‘little tail’ on the top of the D is considerably smaller than the one on the bottom of the D, which can also be caused by something loose in the engraver.

Please test all the set screws with the Allen Key or Hex wrench to confirm that they are tight. Check the belts and wiggle the laser module. Nothing should move under light pressure.