Looks like your y axis is skipping steps... This does happen, and often with alarming regularity. Also the geometry of the part can influence where the skips happen - moving over solid fill usually is the highest-risk of the nozzle dragging, the additional force required pushes over the line of what the stepper can handle. So although it looks like an identical layer every time, it's not the slicer that's doing this! Also, over time the rails/bushings wear, and the friction goes up, so you may have been printing happliy for some time and this has just begun.
Given it doesn't look like you're over-extruding or warping, I'd recommend considering the following:
(1) Ensure the y rails are clean and lubricated
(2) Ensure the y belts are aligned, and the axis moves smoothly
(3) Research tuning the stepper current (Vref), see if you can wind it up a bit without overheating the drivers
If that doesn't fix it, then there are a whole raft of modifications that could improve the situation:
(1) Cool your controller board with a fan (can prevent missing steps due to overheating, particularly if you turn the current up as per (3) above)
(2) Linear bearings and new rails, at least on the y-axis (looks like you were trying to print the lawsy carriages!
)
(3) Bearing replacement of bushing on y driveshaft (lower friction)
(3) Direct-drive y shaft (lower friction again, also big improvement on backlash)
SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi