Welcome @LeoYe, to the community!
Typically, the abbreviation for the COO (Country Of Origin), which is shown here as CHN, refers to the country in which the die (the chip) was manufactured, in this case where the diffusion took place. It may of course be the case that the backend takes place in another country, which can no longer be coded - but that probably doesn't matter, as customs authorities are interested in the origin of the component that determines the function, which is the chip here.
Any further questions regarding COO/COD should be addressed first to your distributor (here Mouser), alternatively to the personal Online Support OLS.
Regards
/Peter
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