In Split 7.2x: Low PHY/High PHY split, The Low PHY/High PHY split is the most acceptable approach for it is less complex and it supports various fronthaul requirements and most importantly it has high virtualization benefits.
Split 7.2x is the O-RAN Alliance fronthaul specification between O-DU to O-RU. It has two variants: 7.2a and 7.2b based on where precoding occurs. If precoding and resource element mapper are part of the O-DU and the O-RRU handles beamforming onwards then it is 7.2a split. If precoding happens in the O-RRU then this is 7.2b split.