Layer shifts destroying perfect prints

hey guys - Im at about 400h print time now - V-Core 4 500 IDEX - its generally working fine and prints good, however I now had 3 prints with massive layer shifts destroying the Parts. It's 100% the same gcode, out of Orca Slicer with my regular PETG profile, it prints fine for the most part even. Printer is 100% stock. Where does this come from, and how can I fix this? Hope someone can help.. 🙏