Users who switch to the new X subscriptions coming soon will receive a prorated refund for their current plan.
That means you’ll be refunded for the unused time left on your existing subscription so you won’t pay twice for the same period.
Update: The X Subscription signup page is still being worked on, adding the info cards and checkout pages. already updated since i first posted.
notable : "We will refund (prorated) all of your current plans above after you have purchased your new subscription. New monthly and annual subscriptions auto-renew until you cancel. Cancel anytime, at least 24 hours prior to renewal to avoid additional charges."