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.
{
    std::map<OutputType, size_t> expected_coins_sizes;
    for (const auto& out_type : OUTPUT_TYPES) { expected_coins_sizes[out_type] = 0U; }
    
    
    expected_coins_sizes[OutputType::UNKNOWN] = 1U;
    CoinsResult available_coins = WITH_LOCK(wallet->cs_wallet, return AvailableCoins(*wallet));
    BOOST_CHECK_EQUAL(available_coins.Size(), expected_coins_sizes[OutputType::UNKNOWN]);
    BOOST_CHECK_EQUAL(available_coins.coins[OutputType::UNKNOWN].size(), expected_coins_sizes[OutputType::UNKNOWN]);
    
    
    
    
    
    
    for (const auto& out_type : OUTPUT_TYPES) {
        if (out_type == OutputType::UNKNOWN) continue;
        expected_coins_sizes[out_type] = 2U;
        TestCoinsResult(*this, out_type, 1 * COIN, expected_coins_sizes);
    }
}
BOOST_FIXTURE_TEST_CASE(wallet_disableprivkeys, TestChain100Setup)