This is happening to me too. The Apple TV app keeps directing me to Peakock even though I already own it through iTunes.
You can still access your purchases copy of the Office but you need to open the iTunes tv shows app, then navigate to purchased, then scroll down to the Office. Of course this is a terrible user experience.
If Apple is doing this to push people to use Peakock (due to a deal with Comcast) and not because of an honest mistake, it’s utterly disgusting and shows Apple no longer values customer experience like it used to. Unless it’s quickly corrected, I’m never buying anything through iTunes ever again and changing all of my channel subscriptions to other providers. They sell you something, then hide it from you and try to sell it to you again through another service. Shameful. I love Apple, but I hope DOJ and Congress investigate so this doesn’t happen again.