Most other phone manufacturers do the same too. It is very common for the CPU frequency to be reduced below 50% battery, or the flashlight to be disabled under

Most other phone manufacturers do the same too. It is very common for the CPU frequency to be reduced below 50% battery, or the flashlight to be disabled under 15% battery, or the LTE modem to switch to single antenna mode (saving power) whenever the camera was on. All of those things are because as the battery ages, it's internal resistance increases, which means the terminal voltage drops a lot whenever it is under heavy load. When the battery voltage is low (ie. nearly empty), and then the terminal voltage drops more due to high load on an old battery, you can dip below the minimum voltage necessary for the voltage regulators and the phone will power off suddenly - even if there might be 20% charge left!. Users don't like their phone randomly turning off before the battery hits nil, so these little tricks are the lesser of two evils. Android even has a special file for the manufacturer to configure all these hacks in!