Ugh, attribution is an absolute nightmare right now. Totally feel you on that - every single platform wants a piece of the credit, and none of the numbers ever line up. It's maddening when you're staring at three different dashboards and they all tell you a completely different story.
the "turn it off and see what happens" test is the only truth-teller, honestly. I've seen it too - pausing Facebook ads barely made a dent, yet Google was claiming something like 60% of revenue came from search. the data was lying, and you only find out when you pull the plug.
One thing I've started doing is using last-click as a rough baseline for reporting, even though I know it's flawed. then I layer in post-purchase surveys asking "how did you first hear about us?". The qualitative answers often reveal blind spots the platforms are totally missing. It's not perfect, but at least it grounds the conversation in something real.
The worst part is having to sound confident to clients when you know the numbers are garbage. i've started giving ranges - "based on what we can measure, paid social is driving somewhere between 20% and 40% of new customers" - and explaining why there's uncertainty. It's uncomfortable, but being upfront beats pretending the data is solid.
How do you handle that? Do you push back and explain the mess, or just give them something actionable and hope it holds up?