Youtube made this change a few weeks ago.
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If you press the OK button twice on your remote after highlighting the info box, should bring another box with publication date up on right hand of screen.
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With all the changes to YouTube regarding both layout and increased ads, I have actually been using an open source front-end (Invidious.io) and watching YouTube that way. Basically, Invidious has their own page layout (depending what instance you use) and allows you to watch YouTube as you normally do (signed in or as guest).
I then just cast Invidious to the Roku (in your case you may be able to cast to your Smart TV directly)
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You can try contacting YouTube here https://support.google.com/youtube/#topic=9257498 and select Submit Feedback.
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You may just find it easier to find alternative ways of getting to your content in your preferred manner rather than dealing with Google, but who knows.
Thanks @AvsGunnar I'll look into Invidious.io.
In the meantime I contacted @YouTubeTV on Twitter and they referred me to https://www.youtube.com/tv/feedback for Roku-specific feedback, so I submitted a message there. I'd encourage anyone else bothered by this change to do the same.
It has nothing to do with reinstalling the App. This is an App (bad) design problem. Certain devices retain the older app ( not upgradeable a?) but most devices will update the app automatically. Send messages to YouTube and Roku to make them aware of the problem and fix it.