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 should say, I have so far changed to scarf joints, changed to normal z-hop and increased a-hop height.

I also increased brim size, even though I had no evidence of lifting.

Yikes. My first instinct would be to check the whole Z-axis for obvious construction defects or parts that are stuck at a certain height.

Another explanation could be your part detaching from the plate at some point and warping upwards, pressing against the nozzle. That would explain the massive sudden buildup of material (and weird one-sidedness of it) and ongoing wobbliness.

Edit: nvmd, just saw your comment about no sign of lifting.

The fact that it is just one side and not even across the z axis tells me that side lifted from warping. Clean your bed with soap and water, use a brim, and if those don't work slow the print down. Long straight lines are prone to warping.

Just seeing this. If you really think this isn't warping print a cylinder tower in the spot where this parts messed up edge was on the bed. If that prints with an issue in the same exact height, it's a problem with your mechanisms, likely z axis.

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.

Is your printer set up on a good, solid countertop? If it rests on something that has any wobble, like a folding table, it can translate into poor prints. The higher off the build plate the print goes, and the faster you run the printer, the part will wiggle a bit without a solid mount. Also make sure all the frame screws are tight.

Dry your petg

This was my first thought. This looks like wobbling to me.
Also, sometimes the slicer isnt that great at generating gcode.

I thought that. It was a fresh roll of elegoo PETG, had silica in and vacuum sealed. More than one print failed in this way too.

We had a bunch of cheapo creality printers on wheeled tables at work. Some of the printers did something similar, so the wobbling was my prime suspect. But there was no correlation between fail and placement. It was printer specific.

Turned out to be issues with the z-axis screw and stabilizers. A good cleaning and, I seem to remember, a new bushing, was all it took.

By no means an expert or super experienced with 3d Printing, but with the few taller prints I have done myself I've noticed print speed plays a big factor. At the higher speeds, the whole structure jiggles a bit, especially with limited supports.

Maybe someone with more experience will confirm or correct me, but slowing the print down would be my first instinct to prevent it.

X axis is off.

Yes. The left to right. Not top to bottom (z)

When the x axis is off, the auto bed leveler can compensate for it. For a while.
Until it gets high off the bed.

Then the skew becomes more problematic as the height increases.

Basically you need to adjust your x to be level on both sides. One side is higher/lower than the other. Probably by 1-2 mm or even less. (On the z rods).

Now I know how to do this on an ender 3 v3. But not your model.

But here is a link to the ender one so you can better understand the issue and how to fix it.

https://www.printables.com/model/853057-x-axis-leveling-blocks-guide-for-ender-3-v3-se

I recommend looking over some of the comments to help explain this issue better and why it's causing the problem you are seeing.

Alternative cause:

If the print is lifting from the plate it can cause a similar issue but those errors would likely be closer to the bottom. But not always.

Is there any lifting or warping of the bottom of the print ?