I'm printing some trays that are thin on the bottom maybe 2mm. Not enough for there to be infill. I'm having the same issue on two completely different printers with different filament and different files. I'm using the same Orca profile for both of them though so it has to be a setting, maybe bed temperature? The sides of the trays are perfect.
Exactly this, the first layer is smooshing and tearing up and that is being carried through the subsequent layers.
Since the bottom is so thin there's no infill layers to reset the density to normal. If there was infill it would build over that damage and then lay fresh new layers on top effectively hiding it unless you're looking at the bottom.
I would also check your hotend, while cold, to make sure it's not loose. It can cause similar issues by dragging the nozzle.