Source

File: wp-includes/comment-template.php

function get_comment_author_IP( $comment_ID = 0 ) { // phpcs:ignore WordPress.NamingConventions.ValidFunctionName.FunctionNameInvalid
	$comment = get_comment( $comment_ID );

	/**
	 * Filters the comment author's returned IP address.
	 *
	 * @since 1.5.0
	 * @since 4.1.0 The `$comment_ID` and `$comment` parameters were added.
	 *
	 * @param string     $comment_author_IP The comment author's IP address.
	 * @param int        $comment_ID        The comment ID.
	 * @param WP_Comment $comment           The comment object.
	 */
	return apply_filters( 'get_comment_author_IP', $comment->comment_author_IP, $comment->comment_ID, $comment );  // phpcs:ignore WordPress.NamingConventions.ValidHookName.NotLowercase
}