Critically Stuck: Why is My Country Codes API Returning Inconsistent Data After Update?

I am completely stuck and frankly, desperate right now. Our Country Codes Directory web tools are returning wildly inconsistent and outdated data from the country codes API after a system update we pushed a few hours ago, and I cannot figure out why this is happening. What are the immediate troubleshooting steps or common causes for such severe data integrity issues after an update? Thanks in advance!