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.

***

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.
{
        
        question_string.append("<hr /><b>");
        question_string.append(tr("Transaction fee"));
        question_string.append("</b>");
        
        
        question_string.append(" (" + tr("%1 kvB", "PSBT transaction creation").arg((double)m_current_transaction->getTransactionSize() / 1000, 0, 'g', 3) + "): ");
        
        question_string.append("<span style='color:#aa0000; font-weight:bold;'>");
        question_string.append(BitcoinUnits::formatHtmlWithUnit(model->getOptionsModel()->getDisplayUnit(), txFee));
        question_string.append("</span><br />");
        
        question_string.append("<span style='font-size:10pt; font-weight:normal;'>");
        if (ui->optInRBF->isChecked()) {
            question_string.append(tr("You can increase the fee later (signals Replace-By-Fee, BIP-125)."));
        } else {
            question_string.append(tr("Not signalling Replace-By-Fee, BIP-125."));
        }
        question_string.append("</span>");
    }
    
    question_string.append("<hr />");
    CAmount totalAmount = m_current_transaction->getTotalTransactionAmount() + txFee;
    QStringList alternativeUnits;
    for (const BitcoinUnit u : BitcoinUnits::availableUnits()) {
        if(u != model->getOptionsModel()->getDisplayUnit())
            alternativeUnits.append(BitcoinUnits::formatHtmlWithUnit(u, totalAmount));
    }
    question_string.append(QString("<b>%1</b>: <b>%2</b>").arg(tr("Total Amount"))