Apple Developer sends out an email notice 30 days before your iOS Distribution Certificate is set to expire. The email will look similar to the image below. Please disregard this notification.
A Distribution Certificate is only needed to upload a new app build. If your brand is uploading a new app build, the developer assigned will create and upload a new iOS Distribution Certificate during the time of the build release.
Sometimes a developer will revoke the certificate of distribution. The developer has to revoke the certificate in order to create a new one. This will not affect live existing build in the App Store. Please disregard this notification.