I’m baffled by this surface. I’ve run the same OrcaSlicer test on many filaments and never saw this problem.
I don’t think wet filament is the problem since the other visible side looks OK and moisture usually causes defects more randomly.
I was tempted to blame excessive cooling by the auxiliary fan, but that does not explain the sharp boundary between the wavy surface and the curved corners.
It looks like the nozzle was unable to maintain travel in a straight line. Maybe turn off the printer and move the head by hand in that area, checking for excess friction?
The problem did not occur at low speeds and it gradually cleared up once “too high” speeds were reached… Belt movement and tension checked recently?
