Your second sentence contradicts your first.
Apple know that battery performance degrades over time. They knew that the batteries they were fitting to iPhones would be unable to supply sufficient current within the normal working life of the phone. They either didn't care about longevity, or chose to prioritise aesthetics. For a company that likes to brag about their environmental credentials and the quality of their devices, that's not a good look.
It's not voltage, it's discharge rate, which is directly proportional to capacity. All else being equal, bigger batteries can supply more current. It hasn't cropped up in the Android camp because Android phones use bigger batteries.
https://batteryuniversity.com/learn/article/what_is_the_c_ra...
Samsung was fined for exactly the same thing Apple was doing.
https://www.businessinsider.com/apple-samsung-5-million-fine...
https://www.theregister.co.uk/2018/10/24/apple_samsung_fined...
Fitting a sufficiently large battery in the first place?
Apple have developed a chronic problem in recent years - stripping out engineering margins in the interests of aesthetics. Fraying MagSafe cables due to inadequate strain relief. "You're holding it wrong". Touch disease and bendgate. Stuck keys because of wafer-thin tolerances on the butterfly keyboard. Macbook CPU throttling due to a marginal thermal solution. Pitifully poor battery durability on EarPods. Display flex cable failures on the MBP.
The minimalist aesthetic has long been a key part of Apple's brand, but they are crossing the line from "minimalist" to "inadequate" with increasing frequency. It's working, for now, but it's eroding their reputation for quality. I've been recommending Macbooks to non-technical users since 2006; I can no longer do so in good conscience, because of the very high price of an entry-level machine and the high probability of a major failure.