You absolutely need to read the lean proof firstly to assess the correctness of the proposition it is proving (ie in this case that it is actually proving or otherwise the smoothness of navier-stokes in R^3 and not something else) and secondly to determine whether the proof is “honest” in the sense given here https://lean-lang.org/doc/reference/latest/ValidatingProofs/

> we use “malicious” to describe code that goes out of its way to trick or mislead the user, exploit bugs or compromise the system. This includes un-reviewed AI-generated proofs and programs.

It is interesting that AI-generated proofs are described as malicious by Lean docs unless reviewed.

reviewing the definitions and theorem statement is a huge amount of work that requires a deep expertise in mathematics and lean. checking correctness of the proof itself can be delegated to machine, checking that the claim that has been proved is free of mistakes is something that still requires much human attention.

If the Lean initial-problem-setup/statements/assumptions/etc. aren't correct then the proof is meaningless. Lean does not know what it is that it is proving i.e. it does not have any semantic understanding but only executes formal logic.

Humans need to verify everything.

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