Search terms from last week are missing but the cost for those days did not change

Almost certainly theirs, and the detail that tells you so is the one you already spotted: the cost did not move. Google only publishes a search term once enough separate people have searched it. Everything below that bar is aggregated away and stays away - it is not a delay, the query never becomes visible later. The cost still lands in the campaign totals, which is exactly why the two numbers disagree. What makes some weeks look worse than others is genuinely just the mix. A week with more long-tail traffic has a bigger invisible share, and there's nothing either of us can do about that. Sanity check if you want one: add up the cost of the search terms you can see and compare it to the campaign cost for the same days. On most accounts the visible portion is somewhere around half of the total and has been for years. If yours has gone from half to a tenth overnight, tell us and we will dig properly.