- Before addressing the horizontal lines you need to address the vertical variation - it’s more fundamental and less likely to have you spinning knobs in software endlessly with no change.
Calibration will get you through that. It’s poorly calibrated now.
- That bit at the bottom is called elephant’s foot, it’s also characteristic of overextrusion, but happens just at the start. It can be minimized but probably never eliminated. Once the machine is extruding the correct amount it can be fine tuned by your Z height calibration, which is incredibly sensitive. The first layer is by far the most important.
I walked through my calibration order here: Snapmaker 2.0 Initial Calibration Settings / Experiences