What type of build plate are you using?
Which brand of PETG-HF are you printing with?
There could be several factors causing this issue. Here are a few possibilities to consider:
Nozzle positioned too close to the build plate (Z-offset too low)
Over-extrusion on the first layer
First layer temperature set too high
First layer printing speed too fast
Uneven or dirty build plate surface
Inconsistent bed leveling or a warped build plate
Excessive or insufficient cooling on the first layer
Incorrect flow rate calibration for PETG-HF
Using a textured build plate instead of a smooth one
Incorrect filament diameter settings in the slicer
Inadequate nozzle pressure relief between extrusions
Inconsistent extrusion due to partial nozzle clogging
Improper adhesion settings (e.g., glue or adhesion sheets affecting flow)
Incorrect acceleration settings causing filament shifts
I’ve printed around 20–30 kg of Bambu Lab PETG-HF so far, but I use a WhamBam Carbon Fiber Plate, which requires higher temperatures for both the bed and the nozzle. However, I stick to the stock speed settings. I experienced first layer issues when my build plate was too cold. If you’re using a WhamBam plate, you can check the temperature settings I use here: