While having a different issue on my confluence instance, I went to "Troubleshooting and support tools" -> "Get help" and told my problem it's supposed to create a ticket and post it to support.atlassian.com (including the support zip file).
When I log in with my email, I shall see that ticket. And when I do, I can't find any issue there.
I tried to create a support issue. Only confluence cloud support seems to be available through the portal nowadays as there's no distinguish between cloud or server/data center products on the icon application picker.