Cloudy Solder Joint

We have been having issues where certain boards we are putting through our routine SMT process will have cloudy solder joints. Some are worse than others. Some boards we will not see this issue at all. Any idea on what can be causing it or if it would be anything rejectable to IPC? We seem to see this on ENIG boards more often. We have attempted to clean this in both our Aqueous bath and Vapor Degreaser but they yield the same results. (for some reason I can't attach a photo, here is a link for an example. https://ibb.co/L9PQJZc )

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