> Do you have a link that explains all this?
No, and I very much doubt any link exists. I am instead guessing based on experience with other govt. agency budgeting and procurement processes. The procurement process is very likely to have been a single bulk buy based on an estimation of upcoming demand. Then demand for the free tests likely did not meet the estimate, leaving a backlog in the warehouse of aging tests. I.e., they likely encountered a real life example of the "beer distribution game" (https://en.wikipedia.org/wiki/Beer_distribution_game).