[This](https://github.com/mozilla/activity-stream/pull/4793/files#diff-28f641d102a3d29e247e48bd7d76bbc9) wasn't a regression. It was part of a round of design tweaks to DS Header that also deprecated subtitle. See "Message" component in design: https://www.figma.com/file/HAk87Z6QBcu6YxBIoXN6LJcU/Firefox-New-Tab-Components-v1?node-id=9%3A16
Bug 1566531 Comment 2 Edit History
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[This](https://github.com/mozilla/activity-stream/pull/4793) wasn't a regression. It was part of a round of design tweaks to DS Header that also deprecated subtitle. See "Message" component in design: https://www.figma.com/file/HAk87Z6QBcu6YxBIoXN6LJcU/Firefox-New-Tab-Components-v1?node-id=9%3A16