Have you tried contacting Roku TV support yet to inquire further? I'd suggest starting there to see what options or suggestions they can provide. Each Roku TV manufacturer provides direct support and warranty services for their products running the Roku OS.
We'd like to know more about how we can help. Can you please provide us with more specific information about the issue you are experiencing? Does the issue only occur on a specific channel or all channels on your Roku device? In addition, can you please specify the exact steps you are taking to reproduce this issue so we can assist you further?
As a first step, we also recommend restarting your Roku player, going Settings > System > Power > System restart > Restart and unplugging your TV for 10-15 minutes then plugging it back in to resolve the issue.