iCloud+: "there is a problem with your payment information" but my card is valid for another year.

I received an email that includes my name, iCloud billing date, and accurate plan information for my particular account, and there is no evidence of spoofing in the email headers. All links in the email link directly to apple.com support info on the official site. I'm including this because I found five other instances of this problem on the discussion site, none of which were resolved successfully, and where the primary suggestion was that it was "phishing." This is clearly not phishing based on the level of detail presented and the lack of any malicious links.

I looked at my payment method and the card on file is in good standing with over a year and a half until expiration. When I went to the App Store settings and viewed my account info, there was no annotation that it needed updating. I went and reviewed the info and saved it (with no changes) just to see if that fixes the problem. Don't know yet until I'm billed.

The email looks official:

"Dear [accurate name], On [normal billing date] you are scheduled to be charged [regular recurring charge] for iCloud+ with [accurate plan sizing] of storage, but there is a problem with your payment information.

Please update your payment information as soon as possible. If we cannot successfully charge your account, it will be downgraded to the free 5 GB plan and your service may be affected."

I am very concerned I will lose data if this is a glitch in the payment system. What should I do to verify that things are correct? Thanks!