That could be some type of particle that is in the diffusion sheets on the screen it self making it focused. You can either just flat out replace the LCD and I would suggest using a guide from ifixit or you can take apart the LCD and look for the affected area and try to clean it.
If you don’t have a clean or low dust area I would not suggest taking the screen apart. I am also not 100% sure about the LCD for that specific iPad but it could also be clamped closed and would be hard to re-seat if moved.
Or if you have a warranty and Apple won’t give you issues about it I would use your warranty since it would be a defect.