Hi!
If you are using Bambu PETG Basic, please try altering the min and max values for the cooling fan in the filament settings from 10/40 to 40/90, see my post here:
I never tried Bambu Labs Petg until now, because I am very happy with extrudr PETG. Beware: Don’t order their XPETG (it’s a matte version of PETG) - this one is a pain for me. I used PETG from extruder in fifferent colors, mostly black and white, but also light and dark grey (see photos), dark green, red, and more.
Bonus: You can print it really fast. I took the “Genereic Petg” profile as a starting point but raised max. volumetric flow from 12 to 20. Obviously, this should be done last, when you are happy with the quality of your prints. I always print on the engineering plate, without glue. Just be sure to wipe it with alcohol from time to time.