Scrambled layers appear on previously good prints

I’ve had my P2S for just over a week, and it had been printing well until yesterday.
The problem is that the print layers now become scrambled for no obvious reason. Here’s a desiccant holder I designed in Fusion 360 and exported as an STL file. The issue first appeared on the fifth print

Normal print.

Scrambled layer.

Here’s what I’ve tried so far:
• Factory reset
• Re‑sent the files from Bambu Studio
• Recalibrated
• Powered off overnight
• Updated to the latest firmware
• Confirmed Bambu Studio is up to date
After wasting a few hours, I tried re‑importing the STL file into a brand‑new project. That worked - the desiccant holder printed correctly again. But after six more prints, the scrambled layer issue returned.
I now have a workaround, but this behaviour suggests the printer is somehow corrupting the .3mf project file.
Has anyone else come across this?