you gotta look at the attribution windows. if you still have 1-day view turned on for meta, it's just stealing credit for google search conversions. turn off view-through attribution and stick to 7-day or 1-day click on meta, then watch the overlap shrink. also, throw a simple post-purchase survey on shopify. when customers actually tell you they came from meta but google claimed the data-driven click, it gives you the real picture to show the client.