80% flow rate needed for good PETG results(??)

Hi,
I'm fairly new to 3D printing. I have printed several things with PETG, using some tips from the internet and never had major problems.
Now I'm using this white filament and although I've already printed nice parts with it, now I'm struggeling with an awfully looking first layer: there's massive stringing on the plain surface, there are brownish chunks of material. I tried "lines" instead of "concentric" shell pattern, which resulted in wavey lines.
When I continue the print the issues get lesser and eventually disappear at higher layers. But it makes me crazy that the first layer is so messed up.

After lot's of experimentation with Z-Offset, temperature, speed and cooling I found that most of these issues get better on 1st layer and go away already at the 2nd when I print with a flow rate of only 80%.
Is this normal? With PLA I always have 100% flow and all is fine.
Also smaller test objects turn out nicely with this filament with 100% flow.

I'm wondering if the lesser flow rate just masks the real issue somehow(?)


I'm using an Artillery Sidewinder X1, so direct extrusion.

it is all relative to the machine, nozzle and the material.. it is a science experiment. There is a setting for filament diameter which should be measured and average actual size input to the slicer.. I have a very different machine than you do, most filaments need 92-93 with mine.. so do what works best for you. I think in one slicer the default filament size is not 1.75 so you may want to make sure that is set right.. good luck