This might be a side effect of your systems updating to Roku operating software version 11.5, which is gradually rolling out right now. It could well be that YouTube needs to update their channel app to be compatible with the new version.
Roku menu path Settings > System > System update will show you your current Roku version number and when it was installed. While there, it never hurts to click on Check now to check for any more recent updates.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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