wired print artifacts

I've upgraded my rr500 to v3.1, since then I get this wired artifacts, normally a clear indicator of under extrusion but it's not. What I did so far: 1. Changed settings like acceleration, print speed etc. 2. Checked everything on the extrusin side, checked configs again and again, wiring, it extrudes what it should Extrude, no skipped steps or similar 3. Changed from orbiter 2.0 back to 1.5 with no difference 4. Changed the rapido UHF because the first one was clogging. 5. Changed my rails/belts and very carefully checked that everything moves smoothly 6. Checked bed tension all the way from too loose to overtightened (changed them afterwards) 7. Used another slicer with fresh settings 8. Manually pushed filament through without any problems, even little "retracts" without any suspicious behavior. 9. Little things I forgot 10. changed temps and other slicer settings So I changed and checked every part of my printer and I don't understand what is going on, I'm out of ideas whats wrong. Solid parts are printing just fine, just outer walls are ugly. Hope that someone has a clue what's going on here ...