Apple has released iOS 12.1.3 today with fixes for bugs. Other OS updates should also be available as well.
Aside from iOS, there is also a supplemental update for macOS. You should download both as soon as you can.
Dr. Mac says he doesn’t usually write about Apple’s minor operating system updates, but, if you’re using an iPhone, iPad, or iPod touch, you should update to iOS version 9.3.5 without delay. Read all about it in Dr. Mac’s Rants & Raves #190: Update your iOS 9.x Devices Now!