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?
{
    return m_subtract_fee_outputs ? m_value : effective_value;
}
CAmount GetSelectionWaste(const std::set<COutput>& inputs, CAmount change_cost, CAmount target, bool use_effective_value)
{
    /
    assert(!inputs.empty());
    /
    CAmount waste = 0;
    CAmount selected_effective_value = 0;
    for (const COutput& coin : inputs) {
        waste += coin.fee - coin.long_term_fee;
        selected_effective_value += use_effective_value ? coin.effective_value : coin.txout.nValue;
    }
    if (change_cost) {
        /
        /
        assert(change_cost > 0);
        waste += change_cost;
    } else {
        /
        assert(selected_effective_value >= target);
        waste += selected_effective_value - target;
    }
    return waste;
}
void SelectionResult::ComputeAndSetWaste(CAmount change_cost)