UPDATE: I figured it out, it's not a Roku issue but an issue with my TV remote. My remote has a button for Prime video and I keep the remote in the storage bin in the arm of my chair. It appears that it gets randomly pushed, and hitting the back button on my roku remote makes it switch back to the Roku input.
I started noticing, especially when getting up from my chair, that Prime video will go to the log on screen even though I'm not in the app. I had assumed that I was hitting the button on the remote, but my remote doesn't have a button for Prime video. It kept happening so I deleted the app from my Roku box since I don't have Prime video anymore but I still have the same issue. When I hit the back button on the remote it puts me right back to what I was watching or the selection screen I was on.
I can't seem to find any information as to why this is going on so I'm hoping someone else can tell me whats going on. This just started about three days ago. My remote battery low warning did come on the screen but I can't imagine that would load to a log in screen and not an actual app.