This is related to #14150 and possibly others, but it's actually a separate issue.

For instance, when using the following query:
`bitcoin-cli scantxoutset start '[{"desc":"wpkh(xpubABCDEF/0/*)", "range":100}]'`
I can get a list of UTXOs, but no way to get back the index which derived that particular UTXO. So it's not much better than deriving on the user side and specifying addresses one by one, so that I already have a cache of addresses to match.

Not sure what the solution looks like. One way is to repeat the full descriptor in the utxo. That might get verbose though.
"\nResult:\n"
            "{\n"
            "  \"bestblock\":  \"hash\",    (string) The hash of the block at the tip of the chain\n"
            "  \"confirmations\" : n,       (numeric) The number of confirmations\n"
            "  \"value\" : x.xxx,           (numeric) The transaction value in " + CURRENCY_UNIT + "\n"
            "  \"scriptPubKey\" : {         (json object)\n"
            "     \"asm\" : \"code\",       (string) \n"
            "     \"hex\" : \"hex\",        (string) \n"
            "     \"reqSigs\" : n,          (numeric) Number of required signatures\n"
            "     \"type\" : \"pubkeyhash\", (string) The type, eg pubkeyhash\n"
            "     \"addresses\" : [          (array of string) array of bitcoin addresses\n"
            "        \"address\"     (string) bitcoin address\n"
            "        ,...\n"
            "     ]\n"
            "  },\n"
            "  \"coinbase\" : true|false   (boolean) Coinbase or not\n"
            "}\n"
            "\nExamples:\n"
            "\nGet unspent transactions\n"
            + HelpExampleCli("listunspent", "") +
            "\nView the details\n"
            + HelpExampleCli("gettxout", "\"txid\" 1") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("gettxout", "\"txid\", 1")
        );
    LOCK(cs_main);
    UniValue ret(UniValue::VOBJ);
    uint256 hash(ParseHashV(request.params[0], "txid"));
    int n = request.params[1].get_int();
    COutPoint out(hash, n);