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.
addtx_count = 0;
    auto handler = HandleLoadWallet(context, [&](std::unique_ptr<interfaces::Wallet> wallet) {
            BOOST_CHECK(rescan_completed);
            m_coinbase_txns.push_back(CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
            block_tx = TestSimpleSpend(*m_coinbase_txns[2], 0, coinbaseKey, GetScriptForRawPubKey(key.GetPubKey()));
            m_coinbase_txns.push_back(CreateAndProcessBlock({block_tx}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
            mempool_tx = TestSimpleSpend(*m_coinbase_txns[3], 0, coinbaseKey, GetScriptForRawPubKey(key.GetPubKey()));
            BOOST_CHECK(m_node.chain->broadcastTransaction(MakeTransactionRef(mempool_tx), DEFAULT_TRANSACTION_MAXFEE, false, error));
            SyncWithValidationInterfaceQueue();
        });
    wallet = TestLoadWallet(context);
    BOOST_CHECK_EQUAL(addtx_count, 2);
    {
        LOCK(wallet->cs_wallet);
        BOOST_CHECK_EQUAL(wallet->mapWallet.count(block_tx.GetHash()), 1U);
        BOOST_CHECK_EQUAL(wallet->mapWallet.count(mempool_tx.GetHash()), 1U);
    }
    TestUnloadWallet(std::move(wallet));
}
BOOST_FIXTURE_TEST_CASE(CreateWalletWithoutChain, BasicTestingSetup)
{
    WalletContext context;
    context.args = &m_args;
    auto wallet = TestLoadWallet(context);
    BOOST_CHECK(wallet);
    UnloadWallet(std::move(wallet));
}
BOOST_FIXTURE_TEST_CASE(ZapSelectTx, TestChain100Setup)