New VC4 prints awful

[rare scaffold]

So, I just finished building VC4 (CoreXY) with standard extrusion setup (Oriter 2 + Rapido Plus 2) and I can't figure out what's the problem with extrusion. In general it prints but there are quite a lot of weird things going on. First layer sometimes looks like is underextruding (picture with yellow filament), or it could be the z-offset to high, but I followed beacon inital configuration and z-offset conifguration. I also did Orca flow test and they look quite alright to me. The printer test print however looks awful. The top layer are quite bad, the bridging failed for small bridges and you can also see one of the round bits is not "complete".

[crimson bolt]

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[rare scaffold]

On the other hand max flowrate test (10 - 30 mm³/s) looks perfect:

And benchy looks pretty good too but if I remember correctly Benchy was printed with 0.4mm nozzle (while all my other prints/tests are with 0.6mm)

[rare scaffold]

Ok. I've been working on the machine again today still trying to fix the belt tention, I also swapped to yet another fresh filament roll and now it prints perfectly. So not really sure what was the problem but it's magically solved.