This is the wall that is side by side to the bath tub.
How do I fix a bathroom wall that has peeled off or separated?
by
Lydia Groom
+4
Plaster the spot sand when dry smooth plasteragain till it looks nice and smooth then paint
I would scape it pack until it is no longer peeling and spray paint it with textured paint, then paint over it with desired color.
Since it has pulled away from the wall, and since it looks like a repair I would never be happy with, I would probably cut it out to see why the repair was made. Probably water damage but I would want to check for mold. Replacing a small section of drywall is a small price to pay to have it done right. There are all kinds of YouTube videos to show you how to replace the section of drywall, tape and mud it. and you can buy that texture (orange peel) in a spray can. Then prime and repaint. Good luck.
I agree with kal, the paper on the drywall has started to separate so any repair you attempt will not stick. That section will need to be replaced. Check this out
https://homeguides.sfgate.com/replace-rotting-drywall-21322.html
Given the location of the damage and the fact that the wall is coming away from beneath the tiles AND that your caulking has come off along the edge of the tub, I would definitely have a professional do this job. The professional could, as kal suggested, cut out the affected section of the wall, investigate for water damage and repair that if necessary, and put in anew piece of drywall. (You could still do painting and resurfacing after that.) And judging by your photo, I would suspect that there is definitely water damage which is what likely caused the drywall to peel. (When drywall gets wet/damp and then dries repeatedly, that is what causes the peeling.) You do NOT want any leaking water in your house. It is the most damaging problem you could have. As for the mold that will inevitably develop in a damp environment, it is highly toxic to humans, particularly children...
It is definitely water damage. Most likely from water coming around the shower curtain or door. It will have to be replaced and make sure you check to see if the water has caused damage under the flooring along the wall and by the tub. Get all damaged areas repaired rather than waiting for other problems. When you replace the water damaged wall, remove damaged area until you get to perfect wall and then some, so that you won't have problems with finishing the replaced wall.