Why the Xiaomi 15 Ultra’s depth of field extension function synthesis is inaccurate?

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The depth of field extension function is a multi-frame depth of field stacking function implemented by an algorithm. After turning on this function, you can get a greater depth of field in certain scenes. However, due to the distribution of depth of field in the scene, when the range of the corresponding object exceeds the algorithm threshold, it cannot be ensured that it is within the synthesis range. This is a normal phenomenon. It does not affect the normal use of other functions of the phone.