I been having the same issue.started to have the same problem with small screen ratio on top left corner and a solution I found is resetting the tv but it's getting annoying.
My screen is only 1/4 of the size. I’ve done everything but factory reset. I’ve had nothing but problems with this device since purchasing. Before my 1/4 screen it would spontaneously return to the Home Screen. I’ve literally had this Roku for two weeks and haven’t been able to watch anything. I wish I would’ve stuck with my Fire Stick.
I had that exact same issue. It didn't matter what channel I tried to watch, once the channel loaded to play video the video was 1/4 screen. It definitely seems to an issue with the HDMI connection; possibly not making good contact with all the pins. I actually discovered it by accident. Since there wasn't any color distortion, I hadn't considered the HDMI cable, but to make sure I had a solid connection, I removed and reconnected the HDMI cable on the TV a few times and that fixed ALL the issues I was having. It did happen again a few days later and I unplug and reconnected the HDMI from the TV and it fixed it again. That was back in February of 2020 and I have not had that issue happen again.