Shapeoko 5 Pro 4X2 - Circles out of round

Is the machine in good mechanical condition? Well lubricated? CNC Machine Maintenance all couplers secure?

If everything electro-mechanically checks out, that leaves my usual concern…

Are you cutting slots just as narrow as the tool? where possible avoid slotting and add geometry and cut as a pocket

and/or

and consider leaving a roughing clearance and taking a finishing pass.