Since the update to Android 4.3 Jelly Bean, some Sony Xperia SP owners have been reporting on a flickering backlight display problem with their handsets. We have attached some videos highlighting the issue, which shows light flickering of the backlight, which we imagine can prove to be quite distracting when trying to read content or view media on your phone.
This appears to be an Android 4.3 bug, as the users did not notice it whilst on the previous Android 4.1.2 firmware. We have only seen reports on this with users on firmware builds 12.1.A.0.266 and 12.1.A.1.201 only. The problem could be related to the kernel as some users on different custom ROMs also report the same issue. Let us know if this is something you have noticed on your Xperia SP since updating to the latest firmware builds.