90% of my prints are made of PETG, and I never had such a problem. Also, I cannot understand what the hype about drying filament is all about. I never did that, and I use spools that are literally years old, sitting on a shelf in the basement of my house, without any protection.
For reference, I took a silver PETG (from goedis, cheap stuff) I openend in March 2020, it’s about 3 years old. I then printed your cube with all settings standard (generic PETG, 0.20 Standard) with flow calibration turned on:
There are clearly some imperfections, but nothing I would worry about, and nothing close to what you are seeing. Either you messed up some settings, or there is something wrong with your printer.