For years, Apple’s iPhones have offered a Low Power Mode to improve battery life when you’re nearing the end of a charge. Low Power Mode is signified by a dull yellow battery charge icon as opposed to green, and disables email fetch, Siri, background app refresh, automatic downloads, some visual effects, and locks the screen within 30 seconds. Now there’s news that Apple may be using a secondary switch to reduce phone performance invisibly when the battery is failing.

Over on Reddit, user Tekfire describes a dramatically different before-and-after scenario on his iPhone 6s. With his original battery, which apparently was at ~80 percent health, his iPhone 6s scored a 1456 in Geekbench 4.2 single-core, and a 2512 multi-core. After he replaced his battery, his score jumped to 2526 single-core and 4456 multi-core. The second set of results appear to be in-line with what the phone should be delivering.

As some of you may remember, roughly a year ago Apple took heat for sudden shutdown issues affecting many iPhone 6s owners. At the time, the company blamed this problem on components left exposed to ambient air for longer than they should’ve been. Apple has apparently adjusted the CPUs inbuilt clock to prevent this problem from prematurely wearing out the battery.

Here’s what we know about the situation so far. First, it may be limited to iPhone 6s smartphones, not other iPhones. Other users without an iPhone 6s don’t seem to be impacted. Second, simply charging the battery does no good and does not resolve the issue. It’s a problem with the battery’s voltage, not the battery’s available charge. Third, this could be a means of preventing the 6s’s original battery from aging too quickly.

Conventional wisdom says withdrawing a great deal of power from the battery very quickly will shorten its lifespan no matter what, though there’s some research that says this is not so. Either way, what we do know is that if you put a heavy drain on a battery repeatedly, you’re going to rack up more charge cycles than if you didn’t. Limiting the clock speed of the CPU or other components outside of low power mode could be a way to prevent users from discharging their batteries too quickly, thereby extending overall battery life.

The problem with this approach, of course, is Apple customers don’t know if it’s crippling their hardware. Other manufacturers might have provided coupons to repair these devices with fresh batteries, but not Apple. Apple — if these rumors are proven true, which we don’t currently know — decided to lower the performance of their smartphones and hope nobody ever noticed. Hopefully this issue turns out to be a bug or affects only a small number of handsets.