iPhone 6s iOS 13.4 Problems
We haven't run into any major bugs or performance issues yet, but some iPhone 6s and iPhone 6s Plus users have.
We've seen complaints about installation issues, UI lag, random reboots, issues with first and third-party apps, Bluetooth problems, issues with Touch ID, and more.
You can expect the list to grow as more iPhone 6s and iPhone 6s Plus users move their device from iOS 12 to iOS 13.4 and iOS 13.0/iOS 13.1/iOS 13.1.1/iOS 13.1.2/iOS 13.1.3/iOS 13.2/iOS 13.2.2/ iOS 13.2.3/iOS 13.3/iOS 13.3.1 to iOS 13.4.
If you're nervous about the current state of iOS 13 problems, you might want to hang back and wait for Apple's next batch of bug fixes.