My PS4 controller developed this drift after about 6 months of use. I doubt I did 2 million cycles though, but I was playing a game that made me push the analog stick harder than it need to be. I got a replacement, and have been using it for over three years now with no problems. I did change my playing habit though: "don't push that joystick so hard, it won't make the character run any faster". So it would seem that you can get the joistick to fail much quicker than after 2 million uses if you push its limits harder.
Quite disappointing, I must say, that Sony used the same type of fail-prone joystick in PS5 controller. You'd think they would have learned a lesson from the PS4 joistuck failures. Most likely they were trying to save a few pennies by sticking with the cheaper joystick. ...."Facepalm"