On power up, +5V (still below) raises quickly to its stable level, while /FAIL (above) looks like the typical capacitor charging curve.
Am I seeing the effect of R112 (3.3kohm) C112 (47uF)?
Ugh, I need to refresh my high-school electronics on RC circuits:
https://www.electronics-tutorials.ws/rc/rc_1.html
So the time constant (τ) is 3.3 * 10^3 * 47 * 10^-6 = 152 ms
The scope captured only 350 ms of the curve, which grows to ~4.2V. Looks about right.