Block editor: How stop media upload if user has already uploaded too many files?

Good afternoon!

I have the following piece of code in wp-config.php:

/**
 * Custom max limit for the total size of a user's media library uploads (in binary bytes).
 *
 */
 define('ML_MAX_QUOTA', 3145728); //3 MB

And in a mu-plugin file I have the following code:

/**
 * Get the collective size in bytes of current user's uploaded media files.
 * @return int The total size of current user's media library uploads.
 */
function jr_current_user_ml_quota() {
    //Calculate the total size of all media files uploaded by user and return the sum as an integer (actual code omitted for simplicity)
}

/**
 * Check how many bytes of data the current user has uploaded to the media library
 * and return an error message if the upload limit has been reached.
 */
function jr_check_upload_limit_reached($file) {

    if (current_user_can('administrator') || !defined('ML_MAX_QUOTA')) {
        return $file;
    }

    $current_quota = jr_current_user_ml_quota();
    $new_quota = $current_quota + $file['size'];

    $upload_limit_reached = ($new_quota > ML_MAX_QUOTA);

    if ($upload_limit_reached) {
        $file['error'] = "File is too large. Delete one or more files to upload more.";
    }

    return $file;
}

add_filter('wp_handle_upload_prefilter', 'jr_check_upload_limit_reached');

The above custom constant + filter callback works great to prevent users from uploading new files to the media library if they have exceeded the defined max quota. However, if a user tries to upload a file directly to a post from inside the block editor, the above code does not work as expected, but instead causes the upload process inside the editor to freeze/hang indefinitely (no error message is displayed).

So my question is: how can I make the above code work properly inside the block editor? I’m guessing I would have to use Javascript? If anyone knows of any beginner-friendly tutorials on how to programmatically customize the block editor, please point me to them!

Thanks.

/jenny ??