There's obviously a piece added to the drywall like a replacement in the hallway.
I don't know how they placed it there but things were not done right all around the house.
We just want to sand it down then put texture and paint so that the line bump is not there but we are concerned that sanding it would cause the drywall replacement piece to fall down because it is on the ceiling.
Best Answer
Drywall is not held to ceilings or walls via mud/tape. The mud/tape is used to hide seams. So sanding should not effect how it is fastened to a wall/ceiling.
In your particular pictures you have a seam that almost surely has tape at the top right in the picture and then a stress crack down to the left. The stress crack may or may not have tape.
I can bet on two things from the picture above...
I don't think there was a repair in this section. Well there could have been but not at the border of the entire crack. It would be very hard and silly to cut out drywall at weird angles. To me this is original job then a crack patched up.
If you do sand it down and do whatever to it after, more than likely whatever you do will end up looking like this. There is a buckling of this drywall going on and sanding it and retopping it may work for 2 months, maybe 6 months but go through a full seasonal cycle and you will be back to this eventually.
What can you do?