The function set_merkle_root does not validate that the new_root is non-zero. If the admin accidentally (or maliciously) updates the root to [0; 32], the sale effectively becomes paused for everyone, as generating a valid Merkle proof for a zero root is cryptographically impossible. While this could be used as an emergency pause feature, the lack of an explicit check increases the risk of accidental "bricking" of the whitelist during updates.

The contract defines the exchange rate as wl_rate_num_sol (Tokens per 1 SOL), which is a single integer. This data structure strictly forces the token price to be less than or equal to 1 SOL. It makes it mathematically impossible to configure a sale for expensive tokens where 1 Token costs more than 1 SOL (e.g., a rate of 0.5 tokens per SOL would require a fractional numerator or a denominator).

The manual call to init_allocation_if_needed is largely redundant because the Anchor constraint init_if_needed (Line 584) already handles the zero-initialization of the account memory. Relying on alloc.buyer == Pubkey::default() to detect a "new" account is valid but unconventional compared to simply trusting Anchor's init process.

The deposit_sale_tokens function performs a state change (moving tokens) but does not emit an Anchor event. This makes it difficult for off-chain indexers and frontends to track when the sale has been funded without monitoring raw SPL Token logs.

The withdraw_sol instruction enforces that funds_destination must be a SystemAccount. This implementation detail prevents the project from setting the withdrawal destination to a Smart Contract Vault, a Multisig PDA, or any account not owned by the System Program. Given that SOL can technically be credited to any account on Solana, this restriction limits the project's ability to use advanced treasury management solutions (e.g., Squads, Gnosis Safe style logic) directly.