The phrase "degraded batteries" refers to batteries that have become less effective or efficient over time. It means that the batteries are no longer able to store or deliver energy as well as when they were new. Full definition
Being able to light up the sensor with the screen of the device and not having to implement an additional lighting solution would allow Samsung to deliver a system that's power - efficient and doesn't degrade the battery performance of existing (Android) flagships. (androidheadlines.com)
In reality, Apple is actually reducing the speed of older devices in order to compensate for degrading battery quality — something early iPhones and Android devices currently aren't capable of doing — which is a smart move on Apple's part. (mobilesyrup.com)
It wasn't that long ago that Apple CEO Tim Cook responded to criticism of Apple for slowing down older devices with degraded batteries in order to prevent them from unexpected shutdown issue. (redmondpie.com)