https://www.occ.gov/news-issuances/news-releases/2022/nr-ia-2022-50.html
APPLICABILITY 11. Does an automatic extension of a credit facility, that was agreed upon by the borrower and the lender at loan origination and memorialized in the loan agreement, constitute a triggering event (i.e., making, increasing, extending or renewing) that would trigger the Federal flood insurance requirements?
No. An automatic extension of a credit facility that was agreed upon by the lender and the borrower at loan origination and memorialized in the loan agreement does not constitute a triggering event (i.e., making, increasing, extending or renewing) that would trigger the Federal flood insurance requirements, because the automatic extension was agreed to in the original loan contract.
However you are stating the extension is built into the security agreement and not the loan agreement. Others may disagree but if the loan agreement (note) does not have the extension agreement then I would have to opine you are extending a designated loan and it would be a MIRE event.