Good evening Jesper and welcome to the Events Calendar Support forum!
Thank you for reaching out to us and for providing your system information.
I would love to help you with this topic.
If I am not mistaken, you are trying to stop RSVP emails from being sent (not WooCommerce tickets). This is why the previous snippet you tried did not work.
Instead, I would recommend trying my colleague George’s great solution: https://theeventscalendar.com/support/forums/topic/disable-rsvp-email-confirmation/#post-1112174
Let me know if that helps.
Have a great day!
Geoff B.