There were a lot of people reporting a similar problem a few months ago following a Roku system update. Most reported a system restart of the affected Roku fixed the problem.
Depending on your Roku model you'll find the "System restart" under "Settings > System > Power", or if you have no Power option, under "Settings > System".
If a restart doesn't do it, or if you don't have sufficient control with the remote to navigate the Roku menus, you can also restart by pulling the power plug to the Roku for a minute or so then plugging it back in.
Roku Community Streaming Expert
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X