Why did India eventually agree to China's terms of disengagement? Because Pangong was becoming too politically heated for Modi during Indian election time and Modi's rivals were on heat charging him of more issues than he is actually responsible for... accusing him of "losing Indian land" which was never India's to begin with and while they were doing that, they accused him of losing more land than what was actually "lost" in terms of PLA occupying it. Lie to yourself and lie against others, whatever it is, it will bite you in the ass and work against you too. In that case Modi's ways were playing for and against him.
Note that disengagement has mostly been for Pangong the highest profile case. Ladakh standoff requires all 20% disputed zone to be resolved either China's way - entire 20% converted to buffer with neither side every stepping foot on it for patrols and de facto control, or India's way - salami slice the 20% until it has greater de facto control and then build on the dispute. What India should do is agree to Chinese buffer offer but demand China demolish the new road from F8 to F5. The alternative is constant stand-off building towards war or perpetual risk of confrontations flaring up. China doesn't seem like it would even consider ceding this 20% to India and nor should it. This isn't Indian land.
I thought it had something to do with running out of oxygen tanks. I guess Jawans need to breathe air after all.