Addition is sinking in the corner to the right.
Posts supporting the deck are buckling.
Concrete foundation is leaning to the right.
Addition is separating.
Retaining Wall is leaning.
Gap between back wall and basement floor.
Gap between garage wall and slab on grade.
Separation of wall to floor filled with foam.
Basement is sloping to the left rear corner.
Take your average home with a view that was built here in the Lower Mainland on a hillside. Now add a few years, if you walked through the house from the front door to the back door you get sea sick or drop a marble on the floor and follow it to where it goes, you might say that you have a failing foundation.
These subtle actions indicate that the foundation is sinking, so go outside and walk around your building as see if it prominently lists in any direction. This can be very visible to the eye or it can appear as an optical illusion. Here are some more of the signs. Cracks may or may not be evident.
Main floor joists lined with beveled shims.
Attic trusses are separating at their plates - fallen off.