PETG corners bulge out

After quite some years of absence from the 3d Printing hobby, I decided to buy a 3d printer again, this time for some practical reasons rather than a hobby (proto-typing, small mounts for parts etc.) I bought the ender 3 v 2 and try to print PETG with it. So far, (I think) the Printer is well calibrated:- The bed is leveled- The prints stick well to the point where I have trouble removing the prints (temporairly heating the bed to 85°c helps removing them while preheating for the next print)- E-Steps & flowrate are adjusted, Temperature for good bridging and little stringing (210-215°c) is found (up to 75° clean overhang without support) But there is one issue, that bothers me: I can't print clean corners. The corners bulge out for some reason. I printed the 20mm measurement cube. The straight surface dimensions are 20mm. The corners bulge out by up to 0.5mm. Both on x & y:https://3dprintboard.com/attachment....1&d=1651601225At first I thougt it might be something due to temperature/shinking but when looking closely, the corners seem to be moved in a given direction:https://3dprintboard.com/attachment....1&d=1651601234This leads me to the thinking that bed/printhead are overshooting. Although there is also some bulging out on the left side of the Y (not as much though)the tension on the belts seems good to me and the print speed in cura is set to @40mm.Any Idea what that is and how to fix it? Oh, and by the way: how do I add line breaks? They seem to disappear as soon as I post/preview although I have seen threads with proper formatted Line Breaks...

slow down, that cube is what 20mm square.. try 25mmS .. turn the temp up, try 230C. Jerk setting maybe to fast, may be over extruding try reducing the extrusion multiplier by 2. Please do not change more than one setting between prints or you will never figure it out. Make sure all your belts and parts are tight, enders are not known for their quality..
Good luck

What has been done?

• All Screws and Belts have been checked at assembly. Some had to be tightened then. (not the root cause)
• Slowing down wall printing speeds (to 20mm/s) helped considerably.
• Jerk setting seemingly had no effect. (found suggestion online to increase jerk setting in order to have no slow down)

to Do:

• According to online recherche, this is a common issue of Bowden setups, as pressure builds up in the bowden tube, which cannot be relieved properly on corner slow-downs.
• Interesting to increase Print temps, I would have guessed it has the opposite effect.
• replace bowden tube vs a better option (or vs direct drive extruder) any suggestions for better bowden tube?
• replacing ender extruder versus a dual gear extruder (likely has little effekt but we'll see)
• Test if tightening the belt further has effect

Currenty in progress:
Replacing y axis vs linear rails and straight heated bed/build plate (likely has no effekt to this issue)