To super specify, yes currently in retail, for 20s the bracket queues are separated. Meaning that xp enabled do not share queues with xp disabled characters
About 2 years ago, blizzard changed the rules for 20s, both f2p and unsubbed “ vets” and lumped them in with xp disabled characters
As a 20, you can be subbed and xpdisabled and still queue for BGs. In NA at least pops are very slow and don’t really pop until late afternoon/ evening EST times
If you plan to play as a veteran unsubbed account, you will still need to re-enable your xp before letting your sub expire in order to be able to queue. But it won’t change the fact that you’ll be in the xp disabled bracket queue.