I would defffff not get that one, It is more expensive and uglier than other ones that look stock and they are lying about the capacity.
The battery says 3.7v (like a normal li-po) and 5.25 watt-hours so 5.25/3.7=1420mah which is the same as the stock iPhone. I have some from amazon that were around 5 bucks and look like a factory replacement.
With lipo batteries, if they start to puff at all you need to get away from them and replace them. I know from rc hobby stuff. I had a couple $500 boats nuclear out on the water. 🙁