Hi Stephen,
Thank you for the detailed information. The 1.8V spike measured on the ISENSE line is not expected, this sounds like a shoot through type of event. This should be triggering the OCP Protection on the DRV8307.
Are you able to zoom in on just one transition between the WHS_GATE signal WLS_GATE Signal? Or monitor this switching on a smaller time scale? If both FETs on side of the bridge are being turned on at the same time that would explain the large amount of current measured on the ISEN line.
Also, we typically do not recommend using thermal reliefs on pads for different power components. I see that your sense resistor as well as bulk and bypass capacitors all have thermal reliefs on their ground returns. Using direct connections will allow for better current flow and for these components to properly dissipate heat into the surrounding ground pours.
The rise times on your Hall IC's also seems suspicious. It looks as though it takes several ms for the signal to transition above the input high threshold, the driver may commutating the motor to slowly, limiting the maximum speed the rotor can spin at by inducing system delay. Is it possible to remove any capacitance on this hall IC line?