We can clearly see here that China's perception of the LAC is the red dotted line, which it had RETREATED to voluntarily at the conclusion of the 1962 Sino Indian war. From China's point of view, the basis for any legitimate LAC has to be based on the 1962 war.
India's perception of the LAC at Pangong Lake is until Finger 8, which the above map shows to be India's claim line based on the Johnson line of 1865. Thus, not based on the 1962 war. India's only real argument for Finger 8 is because China had allowed India to conduct patrols without hindrance up to Finger 8 until this year.
As you can see, China's current perception of the LAC, which it has been vehemently protective of, is based on the positions that PLA had held at the end of 1962 war. Whereas India is claiming up to Finger 8, and other areas beyond it. A quick look at google maps illustrates why this is the case. As indicated on the map above, at Finger 8, there is a chokepoint on the lake itself, which opens up to the eastern half of the lake, at the end of which China's G219 highway runs parallel to.