Vertical lines on screen after replacement, what is broken?

After replacing the screen, I’ve been getting these vertical lines whenever it’s turned on. As you can see from the image, these lines are not random. They go directly through the sides of any light object that appears on the screen. This effect is not as noticeable with other colors, but it still happens. This also only happens a few seconds after the screen is unlocked. I thought the connectors were not properly seated, so I have tried numerous times to connect them again, but the results were the same. I have also tried to clean them, but that did nothing.

There’s two more other things:

1. This phone has water damage. While it is a possible cause for this problem, this phone has been like that for 2/3 years and has had 3 different screens ever since without having this problem.
2. The reason I had to replace the screen was because the phone fell from quite a large height. The screen cracked and popped off. The cables were ripped but they were still connected to the phone. After inspecting the connectors, they seemed intact and had no apparent damage. It seems unlikely, but could this be the cause of the problem?

I was careful when I replaced the screen, I don’t think I have damaged the cables or the connectors of the new screen. Is it possible that the replacement screen itself is defective? It’s from ifixit, so I doubt it, but is it still a possibility?

In any case, I would like to know the cause of the problem I described. Is this a problem with the connectors (and as such, unfixable, since I can’t afford to solder the components), or is it a problem with the screen? Do you think I should try to clean the connectors again? What should I do in my case?