What pictures show alone isn't neccessarily foundation problems. Looks like poor workmanship during some kind of repair. .

Most likely, no room was accounted for for expansion and contraction. The backer-board could have been improperly installed too tightly with no room to expand, or tiles.

Joints between materials need room to expand and contract during seasonal temperature changes to avoid stress that could lead to cracking.

You can see the adjacent drywall pieces at the joint "pushed" together causing the joint compound to arch. My guess would be shrinkage of the wood members in the framing, and probably has been like that for quite a while.

I do not think this specific spot is an indication of a larger foundation problem.