Hardware wallets protect keys, but they protect funds only if their screen shows what is being signed. Complex calldata, EIP-712 messages for unknown contracts and Safe transactions often appear as hashes or hex. Attackers who control the host software or a web front end exploit this: the Bybit Safe theft of February 2025 and many permit-phishing drains worked by getting users to approve something other than what their browser displayed.
Clear signing is the remedy: devices decode calldata and typed data into fields using trusted metadata. ERC-7730 defines a JSON descriptor format for that, with a public registry maintained under the Ethereum organization. Until a device can decode a transaction, verify its hash on an independent machine.