
<!-- 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.

{
    std::string keypath_str = "m";
    for (uint32_t num : keypath) {
        keypath_str += "/";
        bool hardened = false;
        if (num & 0x80000000) {
            hardened = true;
            num &= ~0x80000000;
        }
        keypath_str += ToString(num);
        if (hardened) {
            keypath_str += "'";
        }
    }
    return keypath_str;
}
UniValue decodepsbt(const JSONRPCRequest& request)