`banlist.dat` was introduced in https://github.com/bitcoin/bitcoin/pull/6310, storing nodes that were automatically banned (due to exceeding the misbehavior threshold) and manually banned (through the `setban` RPC).

Automatic bans were removed in https://github.com/bitcoin/bitcoin/pull/19219 and replaced with a discouragement filter. That filter is not saved to disk/persisted over shutdown/startup. The `banlist.dat` therefore now only contains addresses that have been banned through the `setban` rpc.

Since https://github.com/bitcoin/bitcoin/pull/15935, we have a specific file for configuration that is updated through the RPC and persisted over shutdown/startup, namely `settings.json`. We should therefore move the manual ban configuration from `banlist.dat` to `settings.json`. Doing so has a couple of benefits:

- `settings.json` is human readable and easily analyzable by any json parser.
- we wouldn't need to maintain custom [de]serialization code for the `banlist.dat` file.

`banlist.dat` is expected to be fairly small and infrequently updated, so disk space/performance are not huge concerns.
if (g_coin_stats_index) {
        g_coin_stats_index->Stop();
        g_coin_stats_index.reset();
    }
    ForEachBlockFilterIndex([](BlockFilterIndex& index) { index.Stop(); });
    DestroyAllBlockFilterIndexes();
    
    
    
    
    
    if (node.chainman) {
        LOCK(cs_main);
        for (CChainState* chainstate : node.chainman->GetAll()) {
            if (chainstate->CanFlushToDisk()) {
                chainstate->ForceFlushStateToDisk();
                chainstate->ResetCoinsViews();
            }
        }
        pblocktree.reset();
    }
    for (const auto& client : node.chain_clients) {
        client->stop();
    }
#if ENABLE_ZMQ
    if (g_zmq_notification_interface) {
        UnregisterValidationInterface(g_zmq_notification_interface);
        delete g_zmq_notification_interface;
        g_zmq_notification_interface = nullptr;
    }