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.
{
        CTransactionRef tx;
        CCoinControl dummy;
        {
            constexpr int RANDOM_CHANGE_POSITION = -1;
            auto res = CreateTransaction(*wallet, {recipient}, RANDOM_CHANGE_POSITION, dummy);
            BOOST_CHECK(res);
            tx = res->tx;
        }
        wallet->CommitTransaction(tx, {}, {});
        CMutableTransaction blocktx;
        {
            LOCK(wallet->cs_wallet);
            blocktx = CMutableTransaction(*wallet->mapWallet.at(tx->GetHash()).tx);
        }
        CreateAndProcessBlock({CMutableTransaction(blocktx)}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
        LOCK(wallet->cs_wallet);
        LOCK(Assert(m_node.chainman)->GetMutex());
        wallet->SetLastBlockProcessed(wallet->GetLastBlockHeight() + 1, m_node.chainman->ActiveChain().Tip()->GetBlockHash());
        auto it = wallet->mapWallet.find(tx->GetHash());
        BOOST_CHECK(it != wallet->mapWallet.end());
        it->second.m_state = TxStateConfirmed{m_node.chainman->ActiveChain().Tip()->GetBlockHash(), m_node.chainman->ActiveChain().Height(), 1};
        return it->second;
    }
    std::unique_ptr<CWallet> wallet;
};
BOOST_FIXTURE_TEST_CASE(ListCoinsTest, ListCoinsTestingSetup)