memory leak?

[shanliu]

cargo.toml

[package]
name = "aaa"
version = "0.1.0"
edition = "2021"
[dependencies]
sled = "0.34.6"
memory-stats = "1.1.0"
humansize = "2.1.3"

use humansize::{format_size, DECIMAL};
fn main() {
    if let Some(usage) = memory_stats::memory_stats() {
        println!(
            "Current physical memory usage: {}",
            format_size(usage.physical_mem, DECIMAL)
        );
        println!(
            "Current virtual memory usage: {}",
            format_size(usage.virtual_mem, DECIMAL)
        );
    }

    aaaa();

    if let Some(usage) = memory_stats::memory_stats() {
        println!(
            "Current physical memory usage: {}",
            format_size(usage.physical_mem, DECIMAL)
        );
        println!(
            "Current virtual memory usage: {}",
            format_size(usage.virtual_mem, DECIMAL)
        );
    }
}

fn aaaa() {
    let temp_path = "D:/aaa/";
    println!("dir:{}", temp_path);
    // 使用 sled 创建一个数据库
    let config = sled::Config::new()
        .path(temp_path)
        .cache_capacity(1_000_000)
        .mode(sled::Mode::LowSpace)
        .temporary(true);
    let code_db = config.open().unwrap();
    drop(code_db);
    drop(config);
}

output:

Current physical memory usage: 3.87 MB
Current virtual memory usage: 851.97 kB
dir:D:/aaa/
Current physical memory usage: 27.41 MB
Current virtual memory usage: 23.55 MB

Why is the memory not freed when it's already drop db?