MIN_CHANGE is a privacy leak, since it is an easily observable wallet behaviour. Any output almost equal, but minimally larger than MIN_CHANGE is highly likely the change output of a tx.

Also, MIN_CHANGE is quite high, considering the value of bitcoin.

An easy fix for the second issue would be to just lower the value, but maybe some randomization can be done to also fix the first issue?
value_to_select -= output.txout.nValue;
        } else {
            value_to_select -= output.effective_value;
        }
        preset_coins.insert(outpoint);
        /* Set ancestors and descendants to 0 as they don't matter for preset inputs since no actual selection is being done.
         * positive_only is set to false because we want to include all preset inputs, even if they are dust.
         */
        preset_inputs.Insert(output,  0,  0,  false);
    }
    
    for (std::vector<COutput>::iterator it = vCoins.begin(); it != vCoins.end() && coin_control.HasSelected();)
    {
        if (preset_coins.count(it->outpoint))
            it = vCoins.erase(it);
        else
            ++it;
    }
    unsigned int limit_ancestor_count = 0;
    unsigned int limit_descendant_count = 0;
    wallet.chain().getPackageLimits(limit_ancestor_count, limit_descendant_count);
    const size_t max_ancestors = (size_t)std::max<int64_t>(1, limit_ancestor_count);
    const size_t max_descendants = (size_t)std::max<int64_t>(1, limit_descendant_count);
    const bool fRejectLongChains = gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS);
    
    
    if (coin_control.m_avoid_partial_spends && vCoins.size() > OUTPUT_GROUP_MAX_ENTRIES) {