In T131301#8535249, @Physikerwelt wrote:

I realized that it is no longer possible to create new wmflabs.org domains recently. While for humans it might be a good idea to find a domain name that is better to transport the mission of WMF, it is sad that this breaks backward compatibility for IT systems, resulting in failing tests and responsive services. I would vote to allow the recreation of *.wmflabs.org domains.

This task seems completely completely unrelated to what you're talking about, but:

• Existing wmflabs.org proxies are unaffected by the changes, including the ability to update their backends
• If you have a special case which requires a new wmflabs.org proxy, you can talk to the cloud vps admins who can still create them