Similar situation...I received a credit card notification saying my "Purchase for $x.xx at Roku was approved".
I don't have a current Roku subscription, but when I looked at my credit card transactions, I saw that I have a charge for a Britbox subscription that matches the amount indicated as Roku in the notification.
That charge does NOT appear as ROKU in my transaction history, only in the popup notification on my phone.
Anyone else experience this?