
<!-- 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.

{
            RPCHelpMan{"finalizepsbt",
                "Finalize the inputs of a PSBT. If the transaction is fully signed, it will produce a\n"
                "network serialized transaction which can be broadcast with sendrawtransaction. Otherwise a PSBT will be\n"
                "created which has the final_scriptSig and final_scriptWitness fields filled for inputs that are complete.\n"
                "Implements the Finalizer and Extractor roles.\n",
                {
                    {"psbt", RPCArg::Type::STR, RPCArg::Optional::NO, "A base64 string of a PSBT"},
                    {"extract", RPCArg::Type::BOOL,  "true", "If true and the transaction is complete,\n"
            "                             extract and return the complete transaction in normal network serialization instead of the PSBT."},
                },
                RPCResult{
                    RPCResult::Type::OBJ, "", "",
                    {
                        {RPCResult::Type::STR, "psbt", "The base64-encoded partially signed transaction if not extracted"},
                        {RPCResult::Type::STR_HEX, "hex", "The hex-encoded network transaction if extracted"},
                        {RPCResult::Type::BOOL, "complete", "If the transaction has a complete set of signatures"},
                    }
                },
                RPCExamples{
                    HelpExampleCli("finalizepsbt", "\"psbt\"")
                },
            }.Check(request);
    RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VBOOL}, true);
    
    PartiallySignedTransaction psbtx;
    std::string error;
    if (!DecodeBase64PSBT(psbtx, request.params[0].get_str(), error)) {
        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, strprintf("TX decode failed %s", error));
    }