Effect of switching spikes (400ns duration) on capacitor rated voltage
Lifetime of aluminum electrolytic capacitors is generally specified as the time under certain conditions of applied DC voltage, ripple current, and ambient and surface temperature. under these worst case conditions the lifetime is expressed in hours (eg 1000h @90'C).  Thus derating these absolute maximum values leads to multiplier values of lifetime for each of these parameters.

The criteria  is defined by the capacitor’s electrical parameters has drifted out of some specified limit. The ESR is usually first to go, so as self heating temp. rises with ESR, soon the capacitor will either run so hot that it suddenly shorts out or that it ruptures its safety vent and begins to dry out and drift open circuit.  Another failure mode is reverse and over-voltage stress.

CDE uses the criteria for extending Life by Voltage ratio, Mv of applied dc/rated dc;
   Mv = 4.3 - 3.3 Vdc/Vr   ... ref p2 

Thus using Vdc/Vr = 2/3 ratio leads to a lifetime multiplier of 2.1x  while using 0Vdc leads to a lifetime multiplier of 4.3x and full rated voltage = 1x

The actual peak voltage at the cap terminals is what counts for breakdown voltage stress. It must be measured direct across the cap. terminals.

I don't think the ripple voltage in your photo indicates much RMS ripple current so the stress factor for ripple current is low.