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 to create a new one to upload a new build because they don't have an existing certificate available at that time. This will not affect LIVE existing build in the APPSTORE. Please disregard this notification.