Four points to check systematically: (1) version (EN 15804+A2 mandatory for recent declarations), (2) validity date (5 years from publication, stated on the first page), (3) nature of verification (individual third-party or collective, stated in the verification section), (4) functional unit (consistent with the project need, in the first section). If these four elements are in order, the declaration can be used directly in Pléiades / Cypebat / Lesosai without penalty.
Read the source article: Reading an FDES for RE2020: modules, DED, validity