
<!-- Describe the issue -->
Following commit 46004790588c24174a0bec49b540d158ce163ffd (@achow101), `decodepsbt` overstates the fee, apparently including both the `witness_utxo` and `non_witness_utxo` amounts in the inputs.

**Expected behavior**

The decoded fee should be the sum of the inputs, minus the sum of the outputs.

**Actual behavior**

The decoded fee is exactly twice the amount of the inputs, minus the sum of the outputs.

**To reproduce**

Build any PSBT using `createpsbt`, `walletprocesspsbt`, then decode it with `decodepsbt`. See the `fee` field in the JSON.

**System information**

I compiled myself from 5550fa5983ea59e7ccef6540b7ec49a1770fb3ca on Whonix 14.

Then I did `git revert 46004790588c24174a0bec49b540d158ce163ffd ` and the problem went away.

bool extract = request.params[1].isNull() || (!request.params[1].isNull() && request.params[1].get_bool());
    CMutableTransaction mtx;
    bool complete = FinalizeAndExtractPSBT(psbtx, mtx);
    UniValue result(UniValue::VOBJ);
    CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
    std::string result_str;
    if (complete && extract) {
        ssTx << mtx;
        result_str = HexStr(ssTx.str());
        result.pushKV("hex", result_str);
    } else {
        ssTx << psbtx;
        result_str = EncodeBase64(ssTx.str());
        result.pushKV("psbt", result_str);
    }
    result.pushKV("complete", complete);
    return result;
}
UniValue createpsbt(const JSONRPCRequest& request)
{
            RPCHelpMan{"createpsbt",
                "\nCreates a transaction in the Partially Signed Transaction format.\n"
                "Implements the Creator role.\n",
                {
                    {"inputs", RPCArg::Type::ARR, RPCArg::Optional::NO, "The json objects",
                        {
                            {"", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED, "",
                                {
                                    {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The transaction id"},
                                    {"vout", RPCArg::Type::NUM, RPCArg::Optional::NO, "The output number"},