Of course, the ninth major version of Cupertino’s acclaimed operating system is far from unstable, especially after its .2 December maintenance update, but at least one vexing glitch will need to be thoroughly repaired before long.
For the time being, you can dodge it by restarting your iPhone, and ensuring your date and time are set to change automatically. That’s quite an odd workaround for an issue pertaining to battery life, or rather the erroneous displaying of energy consumption and juice left in the tank.
As acknowledged on Apple’s support website, changing the time on an iPhone 6s or 6s Plus manually or even undergoing an automatic adjustment while traveling can break the little battery percentage icon, which might get stuck at a certain misleading value as your cell is slowly depleted of power.
“Apple is aware of this issue and is investigating the cause and a solution.” concludes the official announcement, so most likely, the public, fully polished iOS 9.3 build will contain said universal “solution.”
Source: Apple Support