We do currently show/hide the wallet encryption RPC calls from the help if the current wallet.
In case of an encrypted wallet, encryptwallet is hidden and walletpassphrasechange, walletpassphrasechange and walletlock do appear in the help.
This is no longer ideal in case of multiwallet due to the fact that one may want help infos in order to target a specific wallet.
IMO its preferable to have a static help screen (show everything always). The currently show/hidden calls do handle the possible invalid encryption-state fine.
Fixes #11588