Can UPS electronics degrade over time under normal use?

Yes, while they contain no moving parts, they consist of capacitors, circuit boards, and high power IGBT transistors. These components are susceptible to degradation over time, and can be sensitive to fast-changing humidity, or to airborne chemical contaminants and corrosives. For example, long lasting high temperature/high humidity conditions in a power semiconductor can allow the formation of dendrites, which create a short circuit, and cause device failure. Long term metallic dust buildup on the outside of electrical components can also create the same short circuit condition, with the same resulting failure