This is not unusual and there is a simple explanation. When you add some kind of geometry to a print, the internal preassure inner walls are also different as one changes levels. As filament shrinks, one will see this expressed as horizontal layers lines.
One way to visualize this is by printing a benchy with only one outer wall. You will likely see a line on the wall where the deck meets.
There are some workarounds but the quickest way to test this is to increase the number of walls and also change the print order from the default of inner/outer to outer/inner which will force the outer walls to print first thus allowing the filament to cool and harden faster.
Increase wall loops to create thicker walls.
Other Options
- Another option is to slow down the print. Through the silent mode feature which can only take affect after printing starts. It cuts all movements down to 50%.
- You can try to increase the part cooling fan but that may introduce other artifacts such as poor layer adhesion if it’s turned up too high.
- Increase the layer height either globally or using the variable layer height tool.
- Change the infill pattern to something like Gyroid or 3D triangle. This will vary the internal filament placement and also influence outer wall smoothness.