Thank you for your answer.
I remember that it took like 10 seconds to save the picture. I just realised I had the same problem in February, the picture had more darker lines, kinda like your picture. After that, my phone was getting fixed because of a problem with the 'volume down' button, I mentioned the problem with the photo. But after the repair, they could not tell me if the camera issue was fixed. So now it seems the issue is still there... And I have no idea how we can get this solved..