Strange top surface pattern

[Benleo888 11]

Hi, any UM2+ user encouter the surface printer issue indicated in attach photo?  the repeative pattern happen on every print, this should not be caused by bluid plate not flat, because same problem also happen on top surface on high object.

[geert_2 556]

Fluctuations in temperature, in cooling, or in filament diameter? If it were bent rods, I would expect the pattern to run horizontal or vertical, not diagonal. Or a dirty feeder wheel causing uneven feeding? Just guessing...