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.
auto spk_man = wallet->GetOrCreateLegacyScriptPubKeyMan();
            LOCK2(wallet->cs_wallet, spk_man->cs_KeyStore);
            spk_man->mapKeyMetadata[coinbaseKey.GetPubKey().GetID()].nCreateTime = KEY_TIME;
            spk_man->AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
            AddWallet(context, wallet);
            LOCK(Assert(m_node.chainman)->GetMutex());
            wallet->SetLastBlockProcessed(m_node.chainman->ActiveChain().Height(), m_node.chainman->ActiveChain().Tip()->GetBlockHash());
        }
        JSONRPCRequest request;
        request.context = &context;
        request.params.setArray();
        request.params.push_back(backup_file);
        wallet::dumpwallet().HandleRequest(request);
        RemoveWallet(context, wallet,  std::nullopt);
    }
    
    
    {
        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
        LOCK(wallet->cs_wallet);
        wallet->SetupLegacyScriptPubKeyMan();
        WalletContext context;
        context.args = &m_args;
        JSONRPCRequest request;
        request.context = &context;
        request.params.setArray();
        request.params.push_back(backup_file);
        AddWallet(context, wallet);
        LOCK(Assert(m_node.chainman)->GetMutex());
        wallet->SetLastBlockProcessed(m_node.chainman->ActiveChain().Height(), m_node.chainman->ActiveChain().Tip()->GetBlockHash());