What looks like layer shift?

Hi all,

I am printing a retractable sword (https://thangs.com/designer/3dprinti...20Katana-22696), and I am printing the blades separately using vase mode. It prints flawlessly, until about half-way or 2/3 of the way up, then I start getting what looks like layer shifting (probably not what it is). It's driving me nuts!

I'd appreciate any advice!

Ender 3 S1
eSUN Silk PLA 210deg C nozzle, 70deg C bed
Vase mode/ tried Prusaslicer and Cura
Tightened belts
Updated firmware
Checked that all parts/screws are tight
Adjusted Vref
Rotated 90 blades 90 degrees on bed
0.4mm nozzle, 0.8mm extrusion
Using rafts
Adjusted Z offset/ bed adhesion