Why Xcode compile assets every time even I don't make any change

As title said, I'm using Xcode 12.1, Mbp 15' 2017. My project is a large one that have over 300 images or icons and it will take aboud 45s to compile the assets. I just rebuild it after a success building and it will recompile assets.

What should I do to avoid this problem?
Why Xcode compile assets every time even I don't make any change
 
 
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