It's a common problem. Especially with replacement screens.
It usually has to do with the frames they use during refurbishment. As well as the condition of the corners . if they're bent in or there is any uneven surfaces on the frame (which there is 9/10 times from the drop that caused the crack) then this section will lift. It's usually this left corner because it's the weakest part of the frame. It doesn't have a clip or any support.
Not much can be done unfortunately :/ Aside from getting a 100% original assembly or finding a screen supplier who has excellent frames. I usually advise customers that their bent frame is causing this and it's a good idea to get a case that wraps around the edges. Its cosmetic, and doesn't affect the functionality.