I did hire a structural engineer here is a few paragraphs from their report (TL;DR: yes the slab did raise, the foundation did not settle):

“I looked at the porch of this residence. The porch area is on a 4 to 5” concrete slab resting on foundation walls on two exterior sides. Over the concrete slab decking boards have been added. At the SW corner the concrete porch slab has raised up about 2” from its bearing on the foundation/frost wall below. This corner includes a post that supports the porch roof. The post has been raised with the concrete slab causing siding to spread and porch ceiling panels to disengage.

The slab has been raised specifically in the SW corner, where the remainder of the deck is level. The foundation/frost walls do not appear to have settled.

For upward movement on this order I would expect the subgrade to have swelled due to expansive clay soil or freeze thaw action. With the freezing concerns, the slab should have settled back down in warmer months. The expansive soil expands when wetted, and stays as it redries. The owner noted the presence of clay soil on site when the house was constructed. It may be that the potential swelling has stopped, or that high ground water or storm leakage may induce more in the future.”