Very small absolute changes in that metric are very large relative changes. A conversion rate dropping from 1% to 0.7% is—as you point out—a 30% change in that

Very small absolute changes in that metric are very large relative changes. A conversion rate dropping from 1% to 0.7% is—as you point out—a 30% change in that metric. Or, put in different terms, a drop from 1,000 paying customers to 700 is material and more than a "very small change".