Several PRs are getting the same visual diff issue and causes me to think it may be a flaky test with percy. Examples: https://percy.io/ampproject/amphtml/builds/256910 https://percy.io/ampproject/amphtml/builds/256713 https://percy.io/ampproject/amphtml/builds/256555 https://percy.io/ampproject/amphtml/builds/256464 https://percy.io/ampproject/amphtml/builds/255472 More can be found at: https://percy.io/ampproject/amphtml