Are you implying that the Biblical canon is NOT closed?
Actually, it wasn’t offically “defined” until Trent. Florence didn’t technically “define” it, because books like Sirach were questioned even after Florence:
“[Sirach] is not in the canonical list of Melito of Sardes (c.280AD) or Origen (321.AD) of the Council of Laodicea (360AD). But it is in the list of the Apostolic Constitione (middle of 3rd century, of Gelasius (382AD) and the African Councils of Hippo 393) and Carthage (397AD). But doubts about its canonicity lasted into the Middle Ages, especially under the influence of St. Jerome, who preferred the Palestinian Canon, such doubts lasted even after the Council of Florence (1441) which included it in the list of sacred books without denying its canonicity. It’s canonicity was finally defined at the Council of Trent.”
Fr. William Most, EWTN
Deuterocanonical Books in Canon of Scripture
Also, these later ecumenical councils in the 15th & 16th centuries were not identical to the earlier non-ecumenical councils in the 4th & 5th centuries, which were “missing” some writings & portions of others. And, Jesus held the Jews accountable for knowing what the OT canon was by asking them “Have you not read?” & “It is written” & “the Scriptures say,” etc, indicating the OT canon was “closed” by His time:
Why Protestant Bibles Are Smaller