I have found that anytime you change channels or a new program starts on the one you are watching, 60 seconds later the channel menu that tells you about the program you are watching pops up and takes up half the screen. Is that what you are seeing? Seems roku has been ignoring this programming issue for a long time. Call roku support and report, maybe if enough folks complain they will take us seriously. Good luck.
My TCL Roku 7140X model 43S421 started doing this a few months ago. Likely after a software update. Last year the problem was a green screen on all inputs after a software update. Maybe Roku should stop rolling out updates that basically ruin a TV that worked flawlessly before they forced an update that doesn't work.
It is also happening with other theme packs....try reverting to Roku default theme pack...make sure you change the theme pack and not just the wallpaper etc. Turn off tvafter changing and back on. Good luck!
Please be aware that this issue is still under investigation with the appropriate Roku team. I currently do not have any updates to provide at this time. Once more information is available, I'll be sure to post in this Community thread.