Basically the situation could truly be as simple as this.
1. Both sides mount up further aggression along this disputed section (out of three well known disputed sections this being the most westerly) between 2013 to 2019.
2. China is uncomfortable with Hindu extremism and growing Indian nationalism/chauvinism that resulted in India getting in between Bhutan China talks, causing much drama in Doklam, then taking away Kashmiri self determination, then indirectly threatening CPEC and enhanced engagement with Pakistan (a very important regional ally for China if nothing more than having better access to Iran and the Middle Eastern energy).
3. China observes increased Indian roadbuilding and military infrastructure - helipad/s and permanent camps located very close to the edge of the wishful buffer.
4. China decides to finally make a move and commanded PLA to firmly take everything up to 1992/93 LAC - finger 4 and pp13/14 gora hotsrpings etc.
5. India probably did not expect China to act so decisively and proceed to run around like a headless chicken (media and gov) while IA fail to capture Chinese territory despite attempt/s and fail to unseat PLA.
6. After so many rounds of confidential talks with PLA and China undeniably holding a monumentally huge edge (superior military, superior economy, superior industry, superior positions, superior resources, IA failures), India may have relinquished and backtracked to actually finally fucking observing their own 1992 1993 agreement without patrolling past finger 4.
7. China agrees to keep those details on a low profile and remove PLA from fingers 4 to 8 as India agrees to never set foot back beyond finger 3. India's agreement is as good as agreeing to China's 1959 offer. That's a fact right? It's impossible to deny this even for the dumbest Jai Hinds.
8. India not stepping beyond finger 3 effectively renders their formal claim up to finger 8 as more worthless than Zimbabwean dollar in 2010. But if India or Modi admit to this, there will be Jai Hind outrage. So how to cope how to cope? hmmm. Seems like they want to misrepresent the situation as PLA withdrawing. Okay if that floats your boat and you want to deny India lost finger 3 to 8 privileges i.e. India's 70 year long claim then sure whatever.