The change is nothing to do with uncovering your IP address - it is to stop a way to sneak around your rules.
An example of what used to work:
You have
badguys.com blocked in your uBlock rules
example.com wants to use a tracker supplied by
badguys.com, but you have *.
badguys.com blocked
So,
example.badguys.com is created (which would still be blocked) and also
bg.example.com (which won't be blocked since you want to go to
example.com and use that site)
bg.example.com is a cname (like an alias for a dns record) so now requests to
bg.example.com go to
example.badguys.comYou visit
example.com and the badguys' server sneaks in, since the uBlock never saw
badguys.com being mentioned
This new version of uBlock "uncloaks" the request to
bg.example.com and discovers that it's actually
example.badguys.com. This is why it needs the dns permission, which is what that warning is about.