This differs from behaviour of `importaddress` where it works.
```
$ bitcoin-cli importaddress "<address>" "<label>" false
```
vs
```
$ bitcoin-cli importmulti '[{ "scriptPubKey": { "address": "<address>" }, "timestamp":0, "label": "<label>", "watchonly": true }]' '{ "rescan": false }'
error code: -13
error message:
Error: Please enter the wallet passphrase with walletpassphrase first.
```
bool fLabelFound = false;
    CKey key;
    spk_man->GetKey(keyid, key);
    for (const auto& dest : GetAllDestinationsForKey(key.GetPubKey())) {
        const auto* address_book_entry = wallet.FindAddressBookEntry(dest);
        if (address_book_entry) {
            if (!strAddr.empty()) {
                strAddr += ",";
            }
            strAddr += EncodeDestination(dest);
            strLabel = EncodeDumpString(address_book_entry->GetLabel());
            fLabelFound = true;
        }
    }
    if (!fLabelFound) {
        strAddr = EncodeDestination(GetDestinationForKey(key.GetPubKey(), wallet.m_default_address_type));
    }
    return fLabelFound;
}
static const int64_t TIMESTAMP_MIN = 0;
static void RescanWallet(CWallet& wallet, const WalletRescanReserver& reserver, int64_t time_begin = TIMESTAMP_MIN, bool update = true)
{
    int64_t scanned_time = wallet.RescanFromTime(time_begin, reserver, update);
    if (wallet.IsAbortingRescan()) {
        throw JSONRPCError(RPC_MISC_ERROR, "Rescan aborted by user.");
    } else if (scanned_time > time_begin) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Rescan was unable to fully rescan the blockchain. Some transactions may be missing.");
    }
}
RPCHelpMan importprivkey()