Redirects any traffic to the WooCommerce '/wc/store/checkout' endpoint back to the homepage and logs the attempt in the error_log for review.

Disable WooCommerce Checkout API & Record Attempts

<?php 
function zf_block_and_log_checkout_api_requests() {
	
	$current_url = $_SERVER['REQUEST_URI'];
	$msg_to_log  = 'Checkout API Blocked: ' . $_SERVER['REMOTE_ADDR'];
	    
	if ( strpos( $current_url, '/wp-json/wc/store/checkout' ) !== false ) {	
		error_log( $msg_to_log , 0);   
		wp_redirect( home_url() );
		exit;	
	}

}
add_action('rest_api_init', 'zf_block_and_log_checkout_api_requests');