Why does my printer create notches on the Y surface? Here is an extreme example of notches caused by the printer. They go along all sides but are the strongest on the Y faces. They also happen quite randomly sometimes they are tiny sometimes they are strong. 



I have tightened the belts already and while that reduced the ghosting on the X face a lot, it did nothing on the Y and actually never helped with the notches. This test cube has notches and ripples too but not that strong (the skirting on the bottom of that cube is my fault I set the bed level a little too low).





All models have been sliced with Ultimaker Cura and printed on an Anet A8. Flow = 110&nbsp;%, layer height of 0.1&nbsp;mm for the first example and 0.2&nbsp;mm for the cube, printing temperature = 195&nbsp;°C, no change on jerking and acceleration from default settings. Cube size = 20x20x20&nbsp;mm.

The printer has frame support https://www.thingiverse.com/thing:1672959 but no other upgrades yet.
I see two problems with your printer: your filament seems to overheat in some areas, and you overextrude a little. My suspicion is, that your heating behavior is not well tuned and it overshoots the target temperature, leading to an overcooked filament, then the temperature drops below the temperature you need, leading to a wavy pattern and brown lines.
fixing
I suggest running a PID-tune cycle to get better heating behavior and then recalibrating the printer's extruder.