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.
{
   return !gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET);
}
QString WalletModel::getWalletName() const
{
    return QString::fromStdString(m_wallet->getWalletName());
}
QString WalletModel::getDisplayName() const
{
    const QString name = getWalletName();
    return name.isEmpty() ? "["+tr("default wallet")+"]" : name;
}
bool WalletModel::isMultiwallet() const
{
    return m_node.walletLoader().getWallets().size() > 1;
}
void WalletModel::refresh(bool pk_hash_only)
{
    addressTableModel = new AddressTableModel(this, pk_hash_only);
}
uint256 WalletModel::getLastBlockProcessed() const
{
    return m_client_model ? m_client_model->getBestBlockHash() : uint256{};
}
CAmount WalletModel::getAvailableBalance(const CCoinControl* control)
{
    return control && control->HasSelected() ? wallet().getAvailableBalance(*control) : getCachedBalance().balance;
}