Raised bulge lines on ceiling
This is normal, they are just the seams between the drywall panels. Even the best drywall installers can't make a perfectly level joint. But, a skilled installer will feather them so they are not noticeable under most circumstances.

Based on the shadow, your picture has oblique (low-angle) lighting, it will accentuate the seams. If you have a long wall, put a flashlight near the wall skimming the surface. You should be able to see the seams on your walls also.