
<!-- 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.

{RPCResult::Type::ARR, "inputs", "",
                    {
                        {RPCResult::Type::OBJ, "", "",
                        {
                            {RPCResult::Type::BOOL, "has_utxo", "Whether a UTXO is provided"},
                            {RPCResult::Type::BOOL, "is_final", "Whether the input is finalized"},
                            {RPCResult::Type::OBJ, "missing",  true, "Things that are missing that are required to complete this input",
                            {
                                {RPCResult::Type::ARR, "pubkeys",  true, "",
                                {
                                    {RPCResult::Type::STR_HEX, "keyid", "Public key ID, hash160 of the public key, of a public key whose BIP 32 derivation path is missing"},
                                }},
                                {RPCResult::Type::ARR, "signatures",  true, "",
                                {
                                    {RPCResult::Type::STR_HEX, "keyid", "Public key ID, hash160 of the public key, of a public key whose signature is missing"},
                                }},
                                {RPCResult::Type::STR_HEX, "redeemscript",  true, "Hash160 of the redeemScript that is missing"},
                                {RPCResult::Type::STR_HEX, "witnessscript",  true, "SHA256 of the witnessScript that is missing"},
                            }},
                            {RPCResult::Type::STR, "next",  true, "Role of the next person that this input needs to go to"},
                        }},
                    }},
                    {RPCResult::Type::NUM, "estimated_vsize",  true, "Estimated vsize of the final signed transaction"},
                    {RPCResult::Type::STR_AMOUNT, "estimated_feerate",  true, "Estimated feerate of the final signed transaction in " + CURRENCY_UNIT + "/kB. Shown only if all UTXO slots in the PSBT have been filled"},
                    {RPCResult::Type::STR_AMOUNT, "fee",  true, "The transaction fee paid. Shown only if all UTXO slots in the PSBT have been filled"},
                    {RPCResult::Type::STR, "next", "Role of the next person that this psbt needs to go to"},
                    {RPCResult::Type::STR, "error", "Error message if there is one"},
                }
            },
            RPCExamples {