I have not touched the motor connection since a very long time and I have been testing the drone with the same motor connection for more than 2 months. Had it been the wrong motor connection order, then I would have observed the same on the first day itself.
What I can see in the plot is that, at timestamp 12:06:42.688, all RCOUT had 1161 value and desired roll was -3.61. At the very next timestamp 12:06:42.788, the desired roll becomes 2.39 and there are changes in the RCOUT values.
Also, the landing gears of my drone are small, so as soon as the drone rolled a bit, the propellors touched the ground and it turned upside down.
I can confirm again that the motor connection order is perfectly alright.