Sorry, but this information can be found all over the "HTC One camera purple tint possible fix" thread and the rest of the internet (http://www.anandtech.com/show/7893/t...ne-m8-review/3
"Due to quality control problems with the ST sensor the M8, like later models of the M7, uses the OmniVision sensor exclusively"). The problem is the ST sensors. The newer OmniVision sensors don't seem to have the problem, and that's what they'll install if you send it in for repair.
And as far as my own research shows, the problem does not come back with the newer sensor... haven't seen any consistent claims that show that the new sensor ever has the problems. That HTC uses that same OmniVision sensor in the M8 suggests to me that they haven't had any complaints about it, either.