GST on GTA

ABC Pvt Ltd is a GTA registered under GST(12%).

if ABC Pvt Ltd provides its owned truck to XYZ Pvt Ltd which is again a GTA for movement of some material under LR of XYZ Pvt Ltd. XYZ Pvt Ltd paid freight to ABC Pvt Ltd and bills to third party under RCM whose material is moved.

Now what will be treatment of this transaction.

what is GST Liability of ABC Pvt Ltd if any ??