DC Motor bridge driver L298N. Why separate the tracks after R sense resistors from GND plane?
The L289 datasheet Application Instructions - Suggestions, on page 7, says:


  The sense resistor, not of a wire wound type, must
  be grounded near the negative pole of Vs that must
  be near the GND pin of the I.C.


This ensures that the voltage measured on the sense inputs is all due to the current on that output and not any other currents running through the ground plane causing small additional voltage lifts which would cause errors in the current control.