@Arminda26033
Thanks for the post.
Are you experiencing this issue when only playing content or does it happen when viewing anything on screen? If so, it's possible that there may be a hardware related issue.
Have you tried contacting your TV manufacturer 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 for their products running the Roku OS.
You can reach Hisense Support here: https://www.hisense-usa.com/support/ or at 1-888-935-8880.
Thanks,
Danny
Danny R.
Roku Community Moderator