In the absence of a request from a body mentioned in articles L. 213-1 or L. 752-4 of the Social Security Code or article L. 723-3 of the Rural and Maritime Fishing Code within the time limit set in the first paragraph of article L. 3345-2 of this code, any subsequent challenge to the compliance of the terms of the agreement or regulation with the legal provisions in force at the time of its conclusion may not have the effect of calling into question the tax and social security exemptions attached to the benefits granted to employees in respect of the financial years in progress or prior to the challenge.