Non DNS-compatible service names in consul >= 1.17

In Consul 1.17 release notes there is info about deprecation of illegal DNS service names.

https://developer.hashicorp.com/consul/docs/release-notes/consul/v1_17_x#what-s-deprecated

> Starting with this release, non DNS-compatible service names are deprecated. Consul will only accept lowercase alphanumeric characters and - , and names that start and end with an alphanumeric character. All other characters will be considered incompatible.

Is it true that only lowercase characters are legal? AFAIK, according to RFCs DNS should be case insensitive, so uppercase characters should be allowed as well as lowercase. Can you clarify it?

Is the information available somewhere, in what version the illegal names are going to be removed completely?

Start with the Consul 1.17 release-notes section linked in the issue and verify the stated DNS naming rules against the reported RFC expectation. Done means clarifying whether uppercase names are accepted and documenting the version in which incompatible names will be removed.

Written by the indexing model from the issue text.