this bug has been confirmed for iOS 7 users who have MCPE 0.13.0. what happens is that the backspace key starts acting like a key to move the cursor to the left once. This glitch ONLY happens on iOS 7.0.0 - 7.1.2.
Though keep in mind this ONLY happens on MCPE maps downloaded through safari and pasted into the minecraftWorlds folder through iFile (all of this needs jailbreak)
Thank You Aleksandra Zajac
in my opinion, this is actually not a bug but a new addition to MCPE 0.13.0. It happens on all builds and versions. It's a new shadows-on-text feature i think