A Google Ads view-through conversion may follow an impression without a click or other interaction. It differs from an engaged-view conversion for video.
It is incorrect to say that seeing a banner and later clicking a search ad automatically credits the same purchase to both Google Ads metrics. Across separate platforms, attribution rules differ, so their totals should not simply be added.
Check the relevant Google Ads column and action-specific window. A longer window may increase recorded counts, but those counts do not measure incremental lift. Cookie restrictions and campaign-specific treatment also matter.