Very late answer, but from what I can look up so far it's specifically the 5 II to 5 IV that suffers from this issue...blame Samsung really, even their own phones from this era also have the same saber problem.
The original 5 and 5 V doesn't suffer from this though, my 5 definitely hasn't seen this yet fwiw.
Yeah I'm aware of that, seems to be a software issue which (supposedly) got fixed later on through an update https://www.reddit.com/r/SonyMobile/comments/1e9742u/xperia_1_vi_display_defect/