The parse_comment_query WordPress PHP action fires after the comment query variables have been parsed.
Usage
add_action('parse_comment_query', 'my_custom_function');
function my_custom_function($query) {
    // your custom code here
}
Parameters
- $query(WP_Comment_Query): The WP_Comment_Query instance (passed by reference).
More information
See WordPress Developer Resources: parse_comment_query
Examples
Modify the comment order
Change the comment order to display the newest comments first.
add_action('parse_comment_query', 'newest_comments_first');
function newest_comments_first($query) {
    $query->query_vars['order'] = 'DESC';
}
Exclude comments with a specific word
Exclude comments containing the word “spam” from the comment query.
add_action('parse_comment_query', 'exclude_spam_comments');
function exclude_spam_comments($query) {
    $query->query_vars['search'] = '-spam';
}
Show only approved comments
Modify the comment query to display only approved comments.
add_action('parse_comment_query', 'show_only_approved_comments');
function show_only_approved_comments($query) {
    $query->query_vars['status'] = 'approve';
}
Limit comments per page
Limit the number of comments displayed per page to 5.
add_action('parse_comment_query', 'limit_comments_per_page');
function limit_comments_per_page($query) {
    $query->query_vars['number'] = 5;
}
Exclude comments from a specific user
Exclude comments made by a user with a specific ID.
add_action('parse_comment_query', 'exclude_comments_from_user');
function exclude_comments_from_user($query) {
    $query->query_vars['user_id'] = -1; // Replace -1 with the user ID to exclude.
}