Answer: Add this function to /wp-content/themes/YOUR_THEME/functions.php:

add_filter('comment_flood_filter', '__return_false');

While not ideal, I use the built in comment protocol of WordPress for various unintended purposes, including pentesting. This lead me to find myself in the need of disabling WordPress‘ so called „comment flood protection“. Whatever your reason might be, the solution above will help you solve the error message.