A letter of credit issued or confirmed by an institution that meets the standards prescribed by Section 493.104(b)(2)(C) as of the date the letter is issued or confirmed, but later fails to meet those standards, continues to be acceptable as security under Section 493.104 until the earliest of:
(1) the letter's expiration;
(2) the letter's extension, renewal, modification, or amendment after the date the institution fails to meet those standards; or
(3) the expiration of the three-month period after the date the institution fails to meet those standards.