A user reported to me that they are unable to create a PSBT with a legacy watchonly wallet when they use the GUI. They get an error "The amount exceeds your balance".

I think the issue is that the GUI will retrieve the wallet's balance via `AvailableCoins` before calling `CreateTransaction`. This call to `AvailableCoins` is resulting in fewer coins being returned with recent changes to how `AvailableCoins` works, particularly with additional filtering of spendable coins and preset coins.

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Note that this does not effect descriptor wallets. A workaround for this issue is to switch to using descriptor wallets. An existing legacy wallet can be turned into a descriptor wallet using the `migratewallet` RPC. However many watchonly legacy wallets are likely the result of importing descriptors via `importmulti`. For such wallets, I recommend creating a new descriptor wallet and re-importing the descriptors.
{
    QVBoxLayout* entries = sendCoinsDialog.findChild<QVBoxLayout*>("entries");
    SendCoinsEntry* entry = qobject_cast<SendCoinsEntry*>(entries->itemAt(0)->widget());
    entry->findChild<QValidatedLineEdit*>("payTo")->setText(QString::fromStdString(EncodeDestination(address)));
    entry->findChild<BitcoinAmountField*>("payAmount")->setValue(amount);
    sendCoinsDialog.findChild<QFrame*>("frameFee")
        ->findChild<QFrame*>("frameFeeSelection")
        ->findChild<QCheckBox*>("optInRBF")
        ->setCheckState(rbf ? Qt::Checked : Qt::Unchecked);
    uint256 txid;
    boost::signals2::scoped_connection c(wallet.NotifyTransactionChanged.connect([&txid](const uint256& hash, ChangeType status) {
        if (status == CT_NEW) txid = hash;
    }));
    ConfirmSend();
    bool invoked = QMetaObject::invokeMethod(&sendCoinsDialog, "sendButtonClicked", Q_ARG(bool, false));
    assert(invoked);
    return txid;
}
QModelIndex FindTx(const QAbstractItemModel& model, const uint256& txid)