Microsoft Azure is upgrading platform TLS libraries and support for TLS 1.2 is becoming the standard default. Sitecore xDB Cloud customers running a Sitecore version prior to 9.0 may experience communication errors working with the Sitecore "analytics" index. This can degrade the Sitecore functionality of personalization and other related features.
Identified: On February 26th, Microsoft started applying upgrades to TLS 1.2 for the Azure platform. The Cloud Ops team is working with the Sitecore product teams to address the situation.