It was just normal PLA. The only special filament was some TPU, but that was <10g total.

This is helpful, I think it’s one of 3 things based on your input:

1. Wet filament. That’s causing oozing/build up on the nozzle and causing dragging. Fix: Try drying like you mentioned.
2. The hardware had a failure somewhere. Fix/Verify: ???
3. The firmware is bugging and not setting the Z properly after calibration. Fix/Verify ???