I just noticed this message in the screen after you login, where you launch the game. I’ve always paid by credit card and in account details it shows as continuous or recurring or w/e. I’ve played and paid this way since 2011 with some gaps but since BfA without a gap.
The item says I have less than 7 days and there is a button for “subscribe now”.
I’m a bit mystified why this is so. Account details says my next recurring payment is on 11th which is correct, but my CC isn’t expiring or expired and anyhow I’ve had replacement cards while I’ve been continuously subscribed.
As long as your subscription plan remains active and your payment details remain saved with a card that is not due to expire soon, then it sounds like a “just in case” head’s up and could well be a billing notice bug indeed. Keep a close eye on your renewal that’s coming up, and let our support team know if you experience any issues on that front!