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.
WalletValueMap value_map,
        WalletOrderForm order_form) override
    {
        LOCK(m_wallet->cs_wallet);
        m_wallet->CommitTransaction(std::move(tx), std::move(value_map), std::move(order_form));
    }
    bool transactionCanBeAbandoned(const uint256& txid) override { return m_wallet->TransactionCanBeAbandoned(txid); }
    bool abandonTransaction(const uint256& txid) override
    {
        LOCK(m_wallet->cs_wallet);
        return m_wallet->AbandonTransaction(txid);
    }
    bool transactionCanBeBumped(const uint256& txid) override
    {
        return feebumper::TransactionCanBeBumped(*m_wallet.get(), txid);
    }
    bool createBumpTransaction(const uint256& txid,
        const CCoinControl& coin_control,
        std::vector<bilingual_str>& errors,
        CAmount& old_fee,
        CAmount& new_fee,
        CMutableTransaction& mtx) override
    {
        std::vector<CTxOut> outputs; 
        return feebumper::CreateRateBumpTransaction(*m_wallet.get(), txid, coin_control, errors, old_fee, new_fee, mtx,  true, outputs) == feebumper::Result::OK;
    }
    bool signBumpTransaction(CMutableTransaction& mtx) override { return feebumper::SignTransaction(*m_wallet.get(), mtx); }