It seems that it would otherwise silently skip the rescan for pre-backup used keys that are still waiting to be generated into the keypool?

See also #11249 
{
    return RPCHelpMan{"abandontransaction",
                "\nMark in-wallet transaction <txid> as abandoned\n"
                "This will mark this transaction and all its in-wallet descendants as abandoned which will allow\n"
                "for their inputs to be respent.  It can be used to replace \"stuck\" or evicted transactions.\n"
                "It only works on transactions which are not included in a block and are not currently in the mempool.\n"
                "It has no effect on transactions which are already abandoned.\n",
                {
                    {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The transaction id"},
                },
                RPCResult{RPCResult::Type::NONE, "", ""},
                RPCExamples{
                    HelpExampleCli("abandontransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\"")
            + HelpExampleRpc("abandontransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\"")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
    if (!pwallet) return UniValue::VNULL;
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    LOCK(pwallet->cs_wallet);