Problem areas include fabrics, architectural features like window screens, and in general anything with repeating spatial frequency at a reproduction ratio that puts that spatial detail at close to sensor resolution.
Update: I’ve added examples with a metal-siding building and brush.
Sample image was shot at f/5.6 with the Fujifilm GF 32-64mm. That moiré shows up is a testament to very high resolving power and micro contrast of the lens. At the time, I had no inkling that the image would be severely degraded by moiré, but the results are truly ugly and should be understood as something a professional may have to deal with and be aware of for some subjects.