nikize, my humble apologies, IPv6 is still not supported on App Service. I completely understand this not the answer you wanted hear, we regret any inconvenience with this.
Our product engineering is working on it, but there is no ETA to share on this yet.
Please be assured that I have relayed your feedback to our product team internally.
If you wish you may always share your feedback on our [Uservoice] as well- All of the feedback you share in these forums will be monitored and reviewed by the Microsoft engineering teams responsible for building Azure. Also, Users with a similar request, can up-vote you post and add their comment.
We appreciate your valuable feedback.
-PS. You have posted the question on the right tag(s) [azure-webapps]/