A single failure may not have too much of an impact as the remainder will be able to pick up the slack, although this places them under increased strain.
Ultimately, capacitor failure does have a negative bearing on a UPS’s performance. Filtering ability will suffer and there will be more issues with harmonics and electrical noise. In addition, energy storage volume will decrease, and it can even damage battery strings.
The worst-case scenario of a serious capacitor failure will trigger the UPS to bypass mode, leaving the critical load unprotected.