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.
}
                
                if (IsDust(txout, wallet.chain().relayDustFee())) {
                    if (txout.nValue < 0) {
                        return util::Error{_("The transaction amount is too small to pay the fee")};
                    } else {
                        return util::Error{_("The transaction amount is too small to send after the fee has been deducted")};
                    }
                }
            }
            ++i;
        }
        current_fee = result.GetSelectedValue() - CalculateOutputValue(txNew);
        if (fee_needed != current_fee) {
            return util::Error{Untranslated(STR_INTERNAL_BUG("SFFO: Fee needed != fee paid"))};
        }
    }
    
    
    if (fee_needed > current_fee) {
        return util::Error{Untranslated(STR_INTERNAL_BUG("Fee needed > fee paid"))};
    }
    
    if (scriptChange.empty() && nChangePosInOut != -1) {
        return util::Error{error};
    }
    if (sign && !wallet.SignTransaction(txNew)) {
        return util::Error{_("Signing transaction failed")};
    }