
<!-- 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::OBJ, "final_scriptsig",  true, "",
                                {
                                    {RPCResult::Type::STR, "asm", "The asm"},
                                    {RPCResult::Type::STR, "hex", "The hex"},
                                }},
                                {RPCResult::Type::ARR, "final_scriptwitness", "",
                                {
                                    {RPCResult::Type::STR_HEX, "", "hex-encoded witness data (if any)"},
                                }},
                                {RPCResult::Type::OBJ_DYN, "unknown", "The unknown global fields",
                                {
                                    {RPCResult::Type::STR_HEX, "key", "(key-value pair) An unknown key-value pair"},
                                }},
                            }},
                        }},
                        {RPCResult::Type::ARR, "outputs", "",
                        {
                            {RPCResult::Type::OBJ, "", "",
                            {
                                {RPCResult::Type::OBJ, "redeem_script",  true, "",
                                {
                                    {RPCResult::Type::STR, "asm", "The asm"},
                                    {RPCResult::Type::STR_HEX, "hex", "The hex"},
                                    {RPCResult::Type::STR, "type", "The type, eg 'pubkeyhash'"},
                                }},
                                {RPCResult::Type::OBJ, "witness_script",  true, "",
                                {
                                    {RPCResult::Type::STR, "asm", "The asm"},