Samsung technician authorities can detect cause of that not the ribbon ,one ui 6 bug cause some user wrong update ,not on knox ,they say have high speed connection not the issue ,and based on my forum post last week knox invovle everything with chip and cpu .
I try not to reply but I feel obliged to share based on my knowledge, and experience. LCD or Oled display are based on matrix configuration, therefore if one or more lines is blocked, it causes vertical or horizontal line. While LED itself is very durable, the supply feed which is normally goes through a ribbon cable is not. After some time, it might 'corrode' which causes lines. Some repair shop can clean it using laser, like what is shown in the picture. To add, in some small rare cases, the issue can be caused by software as well. However, it's never caused by knox whatsoever. Knox is always enabled in the software, and it's a security feature, only offered by Samsung for their phones. Hope the above explains well. All the best!
