I recently replaced my aging but well dialled in FLSun Q5 with an Elegoo CC2.
I am very pleased at being able to print much larger things, but I get this effect at height. This is an egregious example but even cleaner prints still have obvious layer shifts.
I had a problem at an exact height every time and it was a tiny bit of dirt on the z screw. I couldn’t see it because it was a white wisp of filament in the threads but after a cleaning and lube the problem went away.