I have no issues printing with ABS. I even did a multicolor ABS print with 3 colors that took 36 hours. Maybe it is the ABS filament you are using. I only use Hatchbox so I don’t have any experience with others.
The PETG might be causing the issue here
Pet g is super prone to absorbing moisture
I would suggest drying out tge PETG for a few hours or simply using a different interface material
Well I tend to agree the heatsink and fan is anaemic not because it may or may not be responsible for your issues but because if the bed temperature is set above warm when printing PLA Bambu thinks we should be deafened by the chamber fan doing a bad job cooling the chamber. It also thinks we should risk warping parts with the Aux fan to help keep the head cool, even when it blows on the wrong side of the head to help with heat sink cooling.