Not able to modify inode metadata

I am working on a ext4 file-system tool that aims to delete files such that they are not recoverable later on. My goal is to clear the inode metadata of a deleted file, but despite my efforts, the changes I make to the inode metadata are not reflecting when I inspect the inode later using stat. Here's the process I follow to modify the inode: 1. Fetch the inode using ext2fs_read_inode. 2. Modify the inode metadata by setting values like i_mode, i_links_count, etc., to zero or NULL. 3. Write the modified inode back to the filesystem using ext2fs_write_inode.

void clear_inode_metadata(ext2_filsys &fs, ext2_ino_t inode_num)
{
    ext2_inode inode;
    ext2fs_read_inode(fs, inode_num, &inode);

    inode.i_mode = 0;                        
    inode.i_links_count = 0;       
    inode.i_size = 0;            
    inode.i_size_high = 0;          
    inode.i_blocks = 0;          
    memset(inode.i_block, 0, sizeof(inode.i_block)); 

    ext2fs_write_inode(fs, inode_num, &inode);  // Write the cleared inode back to disk
}


void delete_file(const string &path, ext2_filsys &fs, const string &device)
{
    ext2_ino_t inode_num = fetch_file(path, fs, device);
    if (inode_num != 0)
    {
        overwrite_blocks(fs, device, path); // traverses extents and writes random data
        clear_inode_metadata(fs, inode_num);
    }

}

The inode metadata stays the same even after invoking clear_inode_metadata(). Also I have a file recovery module that uses a disk snapshot to recover files and to my surprise it is able to recover the file even after I overwrite the file using overwrite_blocks(). The snapshot stores extents used by an inode and the total size of the file. My questions: 1. Why aren't the changes to the inode metadata reflecting after calling ext2fs_write_inode? 2. Why is the file recovery tool still able to recover the file after I overwrite its blocks?