New to 3D printing – infill not connecting and turning into spaghetti (Bambu Lab P2S)

Hi everyone, I’m new to 3D printing and could really use some help. I’m printing on a Bambu Lab P2S and my infill isn’t bonding properly. The walls print fine, but the rectilinear infill doesn’t connect and gets dragged around, creating stringy spaghetti (see photo).

I’m printing PETG at 255 °C nozzle and 70 °C bed. I’ve already done Flow Dynamics and Flow Rate calibration in Bambu Studio, and I’m mostly using default profiles.