Contractual obligations may be secured by a bank guarantee. It must be issued by the bank from the list that meets the established requirements.
The agency specified: the bank must meet the requirements and be included in the named list only at the time of issuing the guarantee. There are no provisions in Law N 44-FZ that such compliance should be maintained throughout the duration of the contract.
If the bank has ceased to meet the requirements, but continues to carry out banking activities, then its guarantee obligations do not cease. No need to change security.
Document: Letter of the Ministry of Finance of Russia dated March 31, 2020 N 24-03-07 / 25499