Clarification on 25k Plan Limit and Workbook Error

How does this 25000 plan limit work? I have this workbook - https://app.clay.com/workspaces/546708/workbooks/wb_GYMhmAjgihEQ/all-tables - where the Find People does not anymore because of this error. Invalid input:

Your source has exceeded your plan's limit of 25000, so future runs will not add new records.

But no matter how I see it I don't get how it even hit the 25k. Can you please clarify?