Thanks for responding. Your experience sounds remarkably similar to mine. My Mac Studio has a Photos library of approximately 166,000 items. After months of severely incomplete Search indexing, I created a new System Photo Library and synchronized it with iCloud. Search initially remained almost nonfunctional. Following an extended period of overnight background processing, visual Search recovered dramatically—for example, searches for "Bird" and "Flower" began returning tens of thousands of results. However, year-based Search remains incomplete, and newly synchronized iPhone photographs sometimes fail to appear in Search. My logs previously showed repeated messages stating "Graph cannot be used because of diverging graph versions (701 vs expected 801)." I haven't established whether that message is related to the taxonomy mismatch you're seeing. My Apple Feedback number is FB24521305. I hope these reports help Apple identify a common cause.